Friction winding shaft

The instant invention relates to a friction winding shaft, in particular for roll cutting and winding machines with a central drive shaft (8) and fitted, adjoining rings (12) on which tubular winding cores (21) are held under pre-stress via winding core retainers 16. According to the invention, winding core supports (27, 28) which automatically press against the inside winding core surfaces (22) after the start of the winding process to provide firm support are proposed. This provides improved centering and alignment of the winding cores (21). For this purpose each ring (12) is divided concentrically into an inner friction ring (17) and an outer holding ring (18) capable of rotation relative to the former. The inner friction ring (17) is provided with a slanted guide (31, 36) through which a pressure rod (29) or a rotatable support element (32) can be extended into a position of contact against the inside winding core surface (22).

BACKGROUND OF THE INVENTION 
The present invention relates to a friction winding shaft, and, in 
particular to a winding shaft for roll cutting and winding machines. 
Roll cutting and winding machines in which wide webs are pulled from a 
supply roll and are then divided into strip-shaped bands are known (German 
DE-OS 28 56 066). The bands are wound up on tubular cores which are placed 
on a friction winding shaft. To wind up the strip-shaped bands, two 
friction winding shafts are provided at a distance from each other so that 
every other strip-shaped band is wound up on one friction shaft and the 
strip-shaped bands in between are wound up on the second friction winding 
shaft. 
As the strip-shaped bands are wound up, different winding diameters are 
produced due to differences in the thickness of the material web, so that 
the winding cores placed on a friction winding shaft can no longer be 
driven at the same rotational speeds. The drive shaft is therefore driven 
at a somewhat higher rotational speed than is required to wind up the 
strip-shaped bands. The rings placed on the drive shaft are slaved by the 
friction contact between the inner ring surfaces and the friction surfaces 
on the pressure elements, but they tend to slip slightly to compensate for 
the difference between the rotational drive speed and the rotational 
winding speed. The force of friction contact can be altered by changing 
the pressure in one of the inflatable hoses placed under the pressure 
elements. 
The pressure elements are in this cases made in form of three pressure 
strips extending in the longitudinal sense of the drive shaft and are 
designed so that they can adapt, at least in the longitudinal sense, to 
different inside diameters of adjoining rings. 
The entire effective length of the drive shaft is taken up by narrow rings 
immediately adjoining each other. This results in identical winding 
tensions in all the bands of the friction winding shaft to be wound up 
since each pressure strip is applied with an identical contact pressure to 
each inside ring surface. 
The rings serving to hold the winding cores are provided with elastic 
projections on the outer ring surface. In particular, sheet metal springs 
are provided which are oriented at a slight angle relative to the radius 
in the direction of drive. The springs are pressed against the inside 
surfaces of the winding cores and function as a spring tension. As the 
bands are wound up, the free, edge-shaped ends of the projections press 
slightly into the material of the winding cores and thus constitute a 
slip-free connection with a winding core. 
In addition, another embodiment of winding core retainers is known on the 
market in form of spring-loaded rotating parts used as clamping elements 
with projecting contact edges across from the outer holder surface. These 
roof-shaped contact edges are also at a slight angle to the radius in the 
direction of drive, and are pressed against the inside winding core 
surface and function as spring tension. 
To remove the wound-up winding cores they are rotated in driving direction 
relative to the stopped rings. This is possible because this rotation is 
in the sense of winding core retainer slant. Rotation in this direction 
and lateral shifting make it possible to remove the winding cores together 
with the wound-up bands from the friction shaft and to install new winding 
cores. 
The winding cores are normally made of a paper material or a plastic with 
relatively wide tolerances. The diameter tolerances of the inside core 
diameter of the winding cores are taken up by the available elastic 
movement of the winding core retainers, so that this available elastic 
movement must be sufficient. 
Because of this elastically supported freedom of movement of the winding 
cores in relation to the rings which is necessary because of the winding 
core tolerances, centering and perpendicular alignment of the winding 
cores in relation to the drive shaft is not sufficiently precise in 
certain instances of application. These minor deviations may result in a 
upward leap and/or in minor wobbling movement which, however small, may 
nevertheless lead to unsatisfactory winding results under certain 
circumstances. A similar winding shaft is known (German DE 39 18 863 A1) 
where the friction rings are provided with slanted guides for the support 
of winding cores. The slanted guide is designed so that the winding core 
supports can be moved within the diameter tolerances of the cores. 
Accordingly, an object of the present invention is to provide a friction 
winding shaft having improved centering and alignment of the installed 
winding cores to prevent upward leaps and wobbling of the winding cores. 
SUMMARY OF THE INVENTION 
The above objectives are accomplished according to the present invention by 
providing a friction winding shaft fitted with a plurality of rings 
wherein each ring is divided into two independent concentric rings, an 
inner friction ring and an outer holding ring. The pressure elements for 
friction connection with the drive shaft are applied to the inside surface 
of the friction ring and the winding core retainers are installed on the 
outer surface of the holding ring. The friction ring and the associated 
holding ring can be rotated relatively to each other. 
At least one slanted guide is provided in the outer surface of the friction 
ring. At least one winding core support is provided on the holding ring 
and engages the slanted guide on the friction ring. The winding core 
support interacts in such a manner that the holding ring may be rotated 
relative to the friction ring in the opposite sense to which the drive 
shaft is driven. The winding core support can be moved beyond the outer 
surface of the holding ring into a pressure position against the inside 
core surface of an installed winding core. The slant and the length of the 
slanted guide are sized so that the winding core support can be moved with 
the existing forces at least within the range of the diameter tolerances 
of the winding cores used. The diameter tolerances are only a few 
millimeters, so that the maximum height of the slanted guide must also be 
sized accordingly. Furthermore the slant selected relative to an orbit 
must not be too steep, so that the adjustment and movement of the winding 
core retainer may be carried out with relatively little force. 
At the beginning of a winding process, the winding cores are placed on the 
friction shaft and are held in position under pre-stress by the winding 
core retainers, whereby centering and lateral alignment may not yet be 
optimal. When the drive shaft begins to rotate after the start, the 
friction ring is rotated at the same time in the same direction through 
frictional interlocking. The holding ring with the installed winding core 
is held back by the tension pull exerted on the band which has already 
been applied, causing the friction ring to rotate first in the rotational 
drive sense relative to the holding ring. The constrained control of the 
winding core supports via the slanted guides on the friction rings is 
thereby actuated in such manner that the winding core supports are moved 
beyond the outer holding ring surfaces until they come into a contact 
position against the inside winding core surfaces. Their constrained 
movement is thereby stopped, and at the same time an intimate closure is 
created between the friction ring and holding ring, so that the two rings 
then continue to rotate together in the same rotational drive sense. 
This firm winding core support (as compared with the known elastic support 
of the winding cores on the elastic or spring-loaded winding core 
retainers) provides improved and movement-free adjustment of the winding 
cores on the friction winding shaft. The actuation and movement of the 
winding core supports is in this case automatic when a winding process 
starts. 
If long winding cores are used, these cover several holding rings. These 
several holding rings are not coupled in their rotational position by the 
sliding clutch via the pressure elements and the mutual free rotatability. 
They adjust themselves differently in their rotational position in 
relation to each other. If only one winding core support is installed on a 
holding ring, winding core supports for several adjoining holding rings 
distributed over the entire angle of rotation are present, so that 
improved centering and alignment is achieved. Preferably three winding 
core supports, offset over the circumference, be provided on one holding 
ring. If winding core supports and the slanted surfaces are of identical 
form, an even, radially aligned movement of the offset winding core 
supports results. A uniform enlargement of the effective circle of contact 
is provided for the winding core. This enlargement is precisely related to 
the center of the drive shaft. Precise centering and alignment of 
relatively narrow winding ores is also possible with this embodiment. 
One embodiment of a winding core support consists of a pressure rod held in 
a radial guide which penetrates the holding ring. Depending on the 
position of the slanted guide, the pressure rod may be moved outward to a 
greater or lesser extent, beyond the outer holding ring surface. 
In another embodiment, the winding core support consists of a rotation 
support element mounted rotatably on a holding ring and penetrating the 
holder. This rotation support element may be made in the form of a bell 
crank, with one crank arm engaging the sloped guide and the other crank 
arm being swivelled out beyond the outer holding ring surface to a contact 
position against the inside winding core surface as the holding ring 
rotates relative to the friction ring. 
The slanted guide on the friction ring may be made in form of an easily 
produced slanted surface on the outer surface of the friction ring. The 
winding core support, in particular a pressure rod, can then slidingly 
directly engage such a slanted surface. A return to the retracted position 
may be effected advantageously via a pull-back spring. 
The slanted guide is also possible in addition or as an option in form of a 
slide guide, whereby the extension and retraction of the winding core 
support is effected necessarily by a sliding connection between a guiding 
element of the winding core support and the slide guide. No pull-back 
spring is required in this case. 
A support in the form of a point or a small surface for the winding cores 
via suitably designed winding core supports results in improved centering 
and alignment of the winding cores. Particularly advantageous results are 
achieved if the support is through a relatively large-surface contact 
element in form of an arc of circle, in form of a shell, towards the inner 
core surface and having a configuration conforming to the inner winding 
core surface. Good, positive-locking contact is achieved if the shell 
element is made of a flexible sheet metal with a radius that is slightly 
greater than that of an inside diameter of a winding core. The spring 
force of the flexible sheet metal should be selected so that the force 
exerted upon the winding core retainer suffices to deform the flexible 
sheet metal so that it applies itself against the inside winding core 
surface. This is also possible if the shell element is part of a rotatably 
mounted support element or if a shell element is connected near the center 
to a pressure rod. 
The utilization of shell elements involves the risk that these may rotate 
in relation to a radial surface and thus become caught on adjoining rings. 
This may cause the entire winding function, which relies in particular on 
free rotatability of the rings in relation to each other, to be disturbed. 
To avoid this, a rotation safety is provided for the winding core 
supports. If shell elements are used, it can be designed with the ends of 
these shell elements bent towards the central drive shaft and thin shims 
installed in the ring diameter. When the winding core retainers or shell 
elements are now moved or swivelled out beyond the outer ring diameter and 
into a contact position, the bent shell element ends are still located 
near the outer shim edge. A rotation relative to a radial plane and 
relative to support rings is prevented by the shim support from becoming 
caught in an adjoining ring. 
An alternate rotation safety may easily be achieved with the utilization of 
a pressure rod by holding the latter prismatically, i.e. not 
cylindrically, in a prismatic guide with a corresponding configuration. To 
install a pull-back spring easily and effectively on a pressure rod, a 
window is provided in the appertaining guide element through which the 
pull-back spring, preferably made of spring wire, can be connected to the 
pressure rod. 
To remove and install new winding cores it is necessary to return the 
winding core supports to their retracted starting position. This may be 
effected in particular with spring-loaded pressure rods by means of a 
back-sliding movement on the slanted guide in combination with a rotation 
of the holding ring relative to the friction ring. The reverse-rotation 
force may however be relatively low if the slanted guide angle is small, 
so that inhibitions may appear, making manual return necessary. To ensure 
reliable return of the winding core support a return spring may be 
installed between the holding ring and the friction ring in such manner 
that it provokes a rotation of the holding ring relative to the friction 
ring in the sense of drive. The spring force of the pull-back spring is 
selected so as to be less than the force between holding ring and friction 
ring produced by the band tension during the winding process. In this 
manner, the relative rotation between the holding ring and friction ring 
is made possible during the winding process in order to move the winding 
core retainer. 
It may also be advantageous with embodiments of a friction winding shaft 
with winding core retainers according to the invention to make the 
pressure elements in form of pressure pads extending in the longitudinal 
direction of the drive shaft, with at least three being provided on the 
circumference, offset in relation to each other. The pressure pads should 
adapt themselves at least in the longitudinal sense to different inside 
diameters of adjoining friction rings. The pressure pads are controlled in 
a known manner by inflatable hoses placed in receiving spaces beneath the 
pressure pads. 
Preferably, the entire active length of the drive shaft should be occupied 
by rings of narrow width, making it possible to easily use winding cores 
with different widths. When shell elements are used on the winding core 
retainers, these are advantageously made in the same width as the rings in 
order to provide the largest possible contact surface. The winding core 
retainers are preferably offset in relation to the winding core supports 
and located between the latter. The winding core retainers are also known, 
spring-loaded rotating elements in form of clamping bodies with contact 
edges projecting beyond the outer holding ring surface.

DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring now in more detail to the drawings, FIG. 1 shows a roll cutting 
and winding machine 1 in which a wide material web 3 is pulled from a 
supply roll 2, and is cut and divided into eight adjoining, strip-shaped 
bands 5. In the same operation the bands 5 are wound up by means of 
friction winding shafts 6, 7, so that one band is wound up on the friction 
winding shaft 6 and the adjoining band on friction winding shaft 7. 
The friction winding shaft 7 is shown in greater detail in FIGS. 2 and 3. 
The friction winding shaft 7 consists of a central drive shaft 8 with 
three longitudinal grooves 9 offset over the circumference, each 
containing a pressure pad 10 pointing outward and a resilient, inflatable 
hose 11. 
Rings 12 are placed on the drive shaft 8 and are shown in detail and more 
precisely in FIGS. 5 and 6. Thin shims 13 are inserted in the outer 
diameter of the rings 12. The rings 12 are in tight contact with each 
other via the shims 13, are rotatable and are held together in axial 
direction by laterally mounted end pieces 14. Tubular winding cores 21 are 
placed on the rings 12 and are held by means of pre-stressed winding core 
retainers 16. The rings 12 are so narrow that generally several rings 12 
are covered by one winding core 21. 
The basic diagram drawing of FIG. 4 shows a partial cross-section through 
the friction winding shaft 7 with a cross-section through an installed 
ring 12. A longitudinal groove 9 with installed pressure pad 10 and 
inflatable hose 11 is shown in the drive shaft 8. The ring 12 is divided 
concentrically into two independent rings, an inner friction ring 17 and 
an outer holding ring 18, which are able to rotate relative to each other 
(arrows 48, 49). The pressure pad 10 is pressed against the inside 
friction ring surface 19. Offset over the circumference, the winding core 
retainers 16 are provided on the outside holding ring surface 20. 
A tubular winding core 21 having an inside diameter that is slightly larger 
than the outside diameter of ring 12 is placed on the holding ring 18. A 
clearance space 23 with a tolerance results between outside holding ring 
surface 20 and inside winding core surface 22. The winding core retainer 
16 consists of a spring-loaded rotating part acting as the clamping 
element 24 (arrow 25 shows the direction of the spring force). The 
clamping element 24, under the influence of spring pre-stress, presses 
with a roof-shaped edge 26 against the inside winding core surface 22 and 
thus bridges the clearance 23. 
To provide a firm support for the winding core 21 by bridging the clearance 
23, the winding core supports 27, 28 are distributed over the 
circumference. The winding core support 27 consists of a pressure bolt 29 
which is capable of movement within a radial guide 30 on the holding ring 
18. With its inside end the pressure bolt 29 bears upon a sloped surface 
31 which extends at an angle to the outer friction ring surface. 
The (alternative) winding core support 28 consists of a rotatable support 
element 32 which is rotatably mounted on the holding ring 18 (rotational 
axis 33) and which engages a slanted slide guide 36 with a cast-on guiding 
element 34. A reverse-rotation spring 37 is provided between the friction 
ring 17 and the holder, and is shown in the form of a spiral compression 
spring. 
In operation, at the beginning of a winding process (FIG. 4), the winding 
cores 21 are placed on the rings 12, and the winding cores being pushed 
and twisted to the right. This causes the edges 26 of the winding core 
retainer 16 which are at an angle relative to a radius to be swivelled 
towards the outside holding ring surface 20 to facilitate installation of 
the winding cores 21. The plurality of winding core retainers 16 are 
offset over the circumference, and hold the winding cores 21 in the shown 
position with clearance 23. The bands to be wound up are now attached to 
the winding cores 21 and the drive shaft 8 is started in the direction of 
drive according to arrow 38. Simultaneously the inflatable hose 11 has 
already been inflated, causing the pressure pad 10 to come into frictional 
contact with the friction ring 17, so that the friction ring, together 
with the drive shaft 8, rotates in the sense of arrow 48. 
At the onset of operation, the holding ring 18 is rotated further to the 
right relative to the shown position (FIG. 4), so that the pressure bolt 
29 and the guiding element 34 lie at the deepest point of the sloped 
surface 31 or the slide guide 36. The pressure bolt 29 and the rotatable 
support element 32 do not protrude beyond the outside holding ring surface 
20 at that moment, so that they do not interfere in the installation of 
the winding cores 21. Because of the free rotatability between the 
friction ring 17 and the holding ring 18, the latter is not slaved 
immediately after the start of the drive shaft 8. Due to the counter-pull 
of the applied bands the holding ring lags behind the rotational movement 
of the friction ring (arrow 48), as is indicated by the segmented arrow 
49. As a result the sloped surface 31 or the slide guide 36 below the 
pressure bolt 29 which is immovably guided on the holding ring or the 
rotatable support element 32 are moved in such manner that a constrained 
movement is carried out until the pressure bolt 29 or the rotatable 
support element 32 come into contact position against the inside winding 
core surface 22. As a result the clearance 23 is firmly bridged (and not 
elastically, as via winding core retainer 16), so that precise centering 
and alignment of the winding cores 21 result. Furthermore the firm 
coupling between the friction ring 17 and the holding ring 18 is then 
established in direction of drive, so that the winding cores 21 then also 
rotate in the direction of drive (arrow 39). 
When the winding cores 21 are to be removed together with wound-up bands, 
the bands are cut off so that the band traction is eliminated. A reverse 
rotation between friction ring 17 and holding ring 18 is then effected via 
pull-back spring 37, so that the (spring-loaded) pressure bolt 29 and the 
rotatable support element 32 are returned to their starting positions. 
FIGS. 5 and 6 show a concrete embodiment of a ring 12 in two side views, 
each with three offset and modified winding core supports 27. The pressure 
bolt 29 is held in a tubular guide 30 which has a window 40 on one side. 
In this window 40, in a slit 41 in the pressure bolt 29, a pull-back 
spring 42 in form of a spring wire is inserted. In addition, 
reverse-rotation springs 43 (arrow 25 in FIG. 6) for the winding core 
retainers are made of spring wire. At the outer end of the pressure bolt 
29 a plane contact element in form of a shell element 44 of the same width 
as ring 12 (see FIG. 5) is fixedly attached. The curvature is 
approximately identical with the outer holding ring surface. Three winding 
core supports 27 are provided at an angular distance of 120.degree. from 
each other, with a winding core retainer 16 in every space between them. 
The outer holding ring surface between the winding core retainers 16 is 
constituted to the greatest extent by the adjustable shell elements 44, so 
that an enlargement of the effective circle of contact for the winding 
cores 21 is achieved through them. 
FIG. 7 shows another modified embodiment of a winding core support 27 in a 
basic diagram. The shell element 44 is in this case made of an 
spring-sheet metal with a curvature (broken line 45) that is greater than 
the inside winding core surface 22. Under load, the shell element 44 then 
presses flat against the inside winding core surface 22. The ends of the 
shell element 44 are bent over into stops 46 to serve as rotation safeties 
in the extended position, and these stops 46 lie within the surface of the 
shims 13 (represented by the segmented circular line 47), even in an 
extended state. A prismatic-shaped pressure bolt 29 is used which can only 
be displaced in a linear manner, cannot be rotated. The prismatic pressure 
bolt is held in a guide (not shown) of corresponding configuration is 
represented as another rotation safety. 
In conclusion it can be said that considerable improvement in the centering 
and alignment of winding cores on friction winding shafts can be achieved 
with the instant invention. 
While a preferred embodiment of the invention has been described using 
specific terms, such description is for illustrative purposes only, and it 
is to be understood that changes and variations may be made without 
departing from the spirit or scope of the following claims.