Note: Descriptions are shown in the official language in which they were submitted.
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Rope guiding device for a rope winch
The invention relates to a rope guiding device for a rope
winch with a rope drum that can be rotated about an axle
for reeling-up or unreeling a rope, on which a guide
element provided with several rope guiding rollers can be
moved parallel to the axle of the rope drum.
Such rope guiding devices are particularly used in drum
winders in the mining industry, where a rope is reeled-up
on a rope drum in multiple rope layers or is unreeled from
it. During the reeling-up or unreeling of the rope,
oscillations occur in the section of the rope ahead of the
rope drum, which make it more difficult to guide the rope
and can affect operational safety. The oscillations are in
particular triggered by a winding system with which the
rope drums are equipped for taking up several layers of
rope, so as to fill each rope layer with reciprocally flush
rope windings and for transferring the rope tidily into the
next rope layer. With known winding systems, the
circumference of the rope drum is divided into two groove
sections with parallel rope grooves, which are reciprocally
offset by half a pitch. Between the two sections there are
the so-called crossover areas, on which the rope is shifted
to the next groove section by half a pitch in the axial
direction of the rope drum.
The incoming or outgoing rope has a natural frequency,
depending on its own weight, tensile load and length. The
jerky shifting of the rope when the rope drum is turning in
the crossover area, causes vibrational excitation of the
rope. If the excitation frequency is close to the natural
frequency of the rope, this can cause vigorous oscillations
of the rope which will impair the safe operation of the
drum winder. The rope can in particular come-off from the
head sheave located on the headgear of the shaft or cause
winding errors on the rope drum. If the oscillations are
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exceptionally strong, any equipment of the drum winder
close to the rope can be destroyed by the wobbling rope.
To avoid such oscillations of the rope, rope guiding
devices for rope winches of drum winders have become known,
in which a guide element is reciprocally shifted
oscillating across the layer width of the rope
synchronously to the rotational angle of the rope drum, to
prevent oscillations in the rope section ahead of the rope
drum.
Such rope guiding device for rope winches of conveying
systems in the mining industry is known from DE 1 932 817.
In order to attenuate the oscillations in the incoming or
outgoing rope, a guide element for the rope which is
designed as a guide carriage is suspended pivoted on a
steering screw, wherein the steering screw forms a part of
a pivotable frame. The rope which runs with clearance
between four horizontally arranged rollers and two vertical
rollers is loaded by the weight of the guide carriage and
the pivotable frame. This is to ensure a safe guidance of
the rope and perfect reeling-up of same onto the rope drum,
while at the same time any oscillations which interfere
with the winding process of the rope in the rope section
which is ahead of the rope drum, will be partially
attenuated.
The known rope guiding devices are complicated and
expensive. The synchronous drive of the guide carriage by
means of a flexible driving link, such as a chain, with the
shaft which also drives the rope drum, is expensive. A
readjustment of the synchronization between the guide
carriage and the drive of the rope drum will be required,
if after shortening the elongated rope the crossover of the
rope from one into the other rope layer changes with
reference to the rotational angle of the shaft and
therefore the rope drum.
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A further rope guiding device with a synchronous drive of
the carriage is known from DE 38 27 078 Al. The rope
guiding device comprises a carriage which has several rope
guiding rollers, where said carriage can be moved parallel
to the axle of the rope drum. The carriage is driven by
means of a threaded spindle with an associated threaded
bush and is supported by means of guide bars. The drive of
the carriage is controlled by means of a control element
according to a winding angle of the rope which adjusts
itself in relation to the drum axle for tracking the
carriage.
Finally, DE 20 54 357 A discloses a rope guiding device for
a rope drive with a rope drum that can be rotated about an
axle for reeling-up or unreeling of a rope, on which a
carriage provided with several rope guiding rollers can be
moved parallel to the axle of the rope drum. On the
carriage, two limiting idlers are arranged one above the
other which can be pivoted and which can be pressed-on by
means of spring pressure against the rope that is reeled-up
on the rope drum. The limiting idlers comprise a partial
area of the rope sheathing. The rope windings which are
formed by the rope that is reeled-up, determine the
traversing motion of the carriage, because the limiting
idlers which positively wrap around the rope shift the
carriage in the direction of the drum axle; the helical
rope winding is translated into a straight-line traversing
motion of the carriage with the aid of the limiting idlers.
Based upon this prior art, the purpose of the invention is
to propose a rope guiding device which has a simpler and
sturdy design, which can be retrofitted in multilayer rope
winches, requires no adjustment operation and at the same
time effectively attenuates the oscillations in the rope.
The solution of this problem is based among other things on
the idea to integrate an additional mass radially into the
rope backlash-free into the rope section ahead of the rope
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drum, in order to prevent oscillation of the rope
effectively in the range of its natural frequency. With
respect to the integrated mass, this involves in particular
the mass of the floating guided guide element itself,
which, depending on operating conditions, can be changed by
additional weights which are to be detachably fitted to the
guide element.
In one aspect, this problem is specifically solved with a
rope guiding device of the type mentioned at the outset, in
that a guide element provided with several rope guiding
rollers each having a roller axle, the rope guiding rollers
being arranged in the guide element such that the rope runs
between the rope guiding rollers backlash-free at least in
the direction of the axle of the rope drum, wherein the
guide element is guided floatingly to be moveable along a
rectilinear direction substantially parallel to the axle of
the rope drum, so that the guide element is moved along the
rectilinear direction exclusively by the forces which are
transferred from the rope to the guiding rollers.
The backlash-free guidance of the rope between the rollers
results in that the rope deflections act directly on the
mass of the guide element. The additional mass of the guide
element shifts the natural frequency of the rope such that
resonance can no longer occur. As a result, the generation
of oscillations in the rope are effectively suppressed,
which are caused in particular by the jerky displacement of
the rope in the direction of the axle of the rope drum
through the crossover areas of the rope winding system.
The floating guide of the guide element parallel to the
axle of the rope drum without utilizing a synchronized
dryer with the rope drum for the guide element accomplishes
that exclusively the forces transferred from the rope to
the guide rollers cause a motion of the guide element
parallel to the axle of the rope drum across its layer
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width. This observation is based upon the fact that the
axle of the rope drum as well as the guide of the guide
element are aligned horizontally during operation, and for
this reason no sloping forces act upon the guide element.
5 The floating guided guide element can be slightly shifted
by the rope in the axial direction of the rope drum, so
that a uniform reeling-up or unreeling of the rope is
ensured.
The rope guiding rollers are supported in the
correspondingly heavy guide element, which itself is
shifted by the rope in the horizontal direction across the
entire layer width of the rope drum. The synchronization of
the rope guide element with the rotational angle of the
driveshaft of the rope drum is dispensed with, since the
guide element which attenuates the oscillations in the rope
due to the backlash-free guidance between the rope guiding
rollers is always in a location where the rope is reeled
onto the drum or is unreeled from it.
A particularly effective backlash-free guidance of the rope
between the rope guiding rollers in direction of the axle
of the rope drum is accomplished in that the guide element
has at least three rope guiding rollers with parallel
roller axles, wherein a further rope guiding roller is
arranged between two outer rope guiding rollers with offset
roller axles in direction of the rope, which constrains the
rope between the two outer rope guiding rollers. In this
context, all roller axles run perpendicular to the axle of
the rope drum, but skew to it.
Constraining the rope between the two outer rope guiding
rollers and the further rope guiding roller can also be
adapted to different operating conditions, in particular to
different rope diameters, if the distance between the
roller axles of at least one of the two outer rope guiding
rollers and the roller axle of the further roller, can be
adjusted. The further roller is preferably supported on an
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articulated pivot arm and is therefore adjustable compared
to the two firmly supported outer rollers.
The guide element comprising the guide rollers is in
particular designed as a roller housing with two sides that
are reciprocally arranged spaced apart, between which the
roller axles of the rope guiding rollers extend. These
sides at the same time serve as bearing housing. Using the
thickness of the sides of the roller housing the mass can
be determined into which the rope is to be integrated
backlash-free.
The floating guide of the guide element parallel to the
axle of the rope drum is done in particular by means of a
linear guide, which enables the translation of the guide
element parallel to the axle of the rope drum at least
across its layer width.
A design of a linear guide that is particularly robust and
durable for mining operations, is a rail guide for a guide
carriage that is firmly connected with the guide element.
The rail guide guides the guide carriage, also called a
transversing bogie, parallel to the axle of the rope drum
at least across its layer width.
In order to integrate an adequate mass into the rope by
means of the guide element under the given spatial
conditions and also for reasons of stability, the guide
element consists preferably of heavy metal, in particular
of iron. The term "heavy metal" does not merely include
various metals, but also their alloys with a density >5
g/cm3. But the guide element can obviously also consists of
other materials having a high density of particularly >5
g/cm3. Using materials with a lower density, which is
basically also possible, requires more installation space,
which possibly may not be available, however.
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If the theoretical calculations of the natural frequency of
the rope of the rope winch differ from the natural
frequency that occurs in practice, then the mass of the
guide element acting as oscillation damper can be changed
by at least one supplementary weight that can be detachably
attached to the guide element. Such changes are also
important in cases when the operating conditions of the
rope winch change as a result of a higher hauling load on
the rope or because of a heavier rope, for example.
In order to facilitate an always perpendicular run of the
rope section ahead of the rope drum to the roller axles of
the rope guiding rollers from a multilayer rope reel, the
length of the rope guiding rollers is larger in the
direction of the roller axles or equal to the difference of
the radius of the rope coil with the rope that is reeled
onto or unreeled from the rope drum. The orientation of the
axles of the axial parallel configured rope guiding rollers
is always perpendicular to the axle of the rope drum and
the longitudinal axis of the rope unreeling from the drum.
In the following, the invention is explained in greater
detail by means of Figures, as follows:
Figure la is a front elevation of a rope drum of a rope
winch,
Figure lb is a side elevation of rope guiding roller
oriented to the rope drum
Figure lc is a section along line X-X according to Figure
la,
Figure 2 is a section through a rope guiding device as
taught by the invention,
Figure 3 is a section along line X-X according to Figure 2
viewed in direction A,
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Figure 4 is a lateral cross-sectional view of the rope
guiding device according to Figure 2,
Figure 5 is a view corresponding to Figure 3, but with an
adjustable rope guiding roller.
Figure 1 a shows a rope drum (1) of a drum winder, which
serves for driving the hoisting cages or hoisting buckets
in the mining industry. The illustrated embodiment refers
to a rope drum (1) with a cylindrical drum core (2), the
lateral borders of which are flanges (3). A rope (4)
connected with the hoisting cage and/or hoisting bucket is
unreeled from the drum core (2) as the rope unwinds and is
reeled-up in multiple rope layers as the rope is wound up.
The drum core (2) is equipped with a winding system in
order to reel-up the rope (4) in multiple rope layers with
rope windings that are reciprocally flush across the entire
layer width (6) and to transfer it tidily into the next
layer (Sa - 5d)). The winding system divides the
circumference of the drum core (2) into two sections (7a,
7b) with parallel grooves which are reciprocally offset by
half a pitch. Between the areas (7a, 7b) with parallel
grooves, the so-called crossover areas (8a, 8b) are
located, on which the rope (4) is shifted by half a pitch
in the direction of the axle (9) of the rope drum (1) to
the next grooved area (7a and/or 7b), while the rope drum
(1) is rotating. The jerky shifting of the rope (4) from
one grooved area (7a and/or 7b) into the next while the
rope drum (1) is rotating, excites
oscillations in the rope section of the rope that is ahead
of the rope drum (1). If the excitation frequency is within
the range of the natural frequency of the rope (4), violent
deflections of the rope (4) can occur which can
significantly impair the operational safety of the drum
winder.
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The rope guiding device (11) as taught by the invention is
used for the purpose of preventing rope deflections as a
result of vibration excitations. The rope guiding device
(11), illustrated schematically in Figure 2, shows the rope
(4) exiting from the rope drum (1) according to Figure 1 at
an angle of lapping a of approximately 45 to a horizontal
head sheave (not shown). The rope angle of lapping a to the
horizontal can however also comprise other angles between -
90 to + 90 degrees.
The rope guiding device (11) comprises a guide element that
is formed by a roller housing (12) and a guide carriage
(13), also termed a traversing bogie, located below the
roller housing (12). The roller housing (12) is mounted on
the guide carriage (13) top surface (14) which is tilted
corresponding to the rope angle of lapping a of
approximately 45 , in particular by welding or by the use
of bolts and screws. The roller housing (12) comprises two
parallel sides (15a, 15b) which are arranged spaced apart,
between which the three roller axles (16 a-c) for
accommodating two outer rope guiding rollers (17 a, b) as
well as a center rope guiding roller (17 c) arranged
between the two outer rope guiding rollers, extend.
From Figure 3 it can be recognized that all roller axles
(16 a-c) run reciprocally parallel. The roller axles (16a,
b) of the two outer rope guiding rollers (17a, 17b) are
arranged reciprocally offset in the rope direction (18) of
the rope (4). On the opposite side of the rope (4), axially
parallel to the roller axles (16a, 16b) of the outer rope
guiding rollers (17a, 17b), the roller axle (16c) of the
center rope guiding roller (17 c) is located, which
slightly clamps and therefore constrains the rope between
the two outer rope guiding rollers (17a, 17b). In the
clamping area, the rope (4) is a little deflected by the
center rope guiding roller (17 c) from the rope direction
(18) in the direction of the two outer rope guiding rollers
(17a, b). As a result, the rope (4) is guided backlash-free
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between the rope guiding rollers (17 a-c). The backlash-
free rope guiding effectively prevents deflections of the
rope (4) in direction of the axle (9) of the rope drum (1).
In the direction of the roller axles (16 a-c), the movement
5 of rope (4) between the rope guiding rollers is inhibited
because it is wedged, so that any potential deflections of
the rope which could occur in this direction are attenuated
effectively by the guide element from the roller housing
(12) and guide carriage (13). Potential rope deflections
10 directly affect the total mass of roller housing (12) and
guide carriage (13), which in particular consist of iron or
iron alloys.
The guide carriage (13) carrying the roller housing (12) is
guided floating by a rail guide (19) parallel to the axle
(9) of the rope drum (1). In order to reduce the friction,
the guide carriage (13) is supported in the rail guide (19)
on four rollers (21). The rail guide (19) is fixed so that
it cannot be shifted. Floating guidance means that the
guide element comprising the guide carriage (13) and the
roller housing (12) without using its own drive is
exclusively moved by the rope (4) which runs backlash-free
between the rope guiding rollers (17 a-c) along the rail
guide across the layer width (6).
Any potential rope deflections of the rope (4) therefore
act directly on the total mass of the guide element,
wherein the additional mass of the guide element shifts the
natural frequency of the rope to such an extent that
resonance can no longer occur. Due to the missing
synchronization with the rotational angle of the rope drum
(1), the guide element of the rope guiding device will
always be in a position where the rope just reels-up onto
the rope drum and/or unreels from it.
Figure 5 shows an embodiment of the guide element, in which
the center rope guiding roller (17c) in the roller housing
(12) is adjustable, in order to be able to adapt the rope
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guiding device to different operating conditions, in
particular to rope diameters. For this purpose, the center
rope guiding roller (17 c) is not directly supported in the
two opposite sides (15a, 15b), but in one support frame
(23) which can be pivoted around an axle (22). The
adjustment is done by means of an adjusting screw (24),
which displaces the support frame (23) in direction of the
rope (4) and thus the center rope guiding roller (17 c) in
direction of the two outer rope guiding rollers (17a, 17b),
and therefore constrains the rope. An internal thread in a
link (26), which extends between the sides (15a, 15b) of
the roller housing (12) serves as an abutment for the
adjusting screw (24).
The length (25) of the rope guiding rollers (17 a-c) in
direction of the roller axles (16 a-c) is preferably the
same as the difference of the radius of the rope coil of
the rope (4), if it is completely reeled-up and completely
unreeled from the rope drum (1), as can be seen from
Figures lb and lc in particular.
An essential advantage of the rope guiding device (11) as
taught by the invention consists in that a complex
synchronous coupling of the guide element to the driveshaft
of the rope drum (1), can be dispensed with. For this
reason, it is possible that the rope guiding device (11)
can be retrofitted on any drum winder.
The floating support of the guide element prevents winding
errors, even following any potential shortening of the
rope, since the guide carriage with the rope guiding
housing automatically follows the movement of the unreeling
rope in the direction of the axle of the drum across the
layer width (9).
The design of the rope guiding device is simple, sturdy,
and therefore durable. The technology of the rope guiding
device is also easily comprehensible for drum winder
operators. By appropriate adaptation of the guide carriage,
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in particular of the angle of inclination of its top
surface (14), the guide element can be easily adapted to
various rope angles of lapping.
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List of reference symbols
No. Description
1 Rope drum
2 Drum core
3 Flanges
4 Rope
5a-d Layers
6 Layer width
7a-b Section with parallel
grooves
8a-b Cross-over area
9 Rope drum axle
11 Rope guiding device
12 Roller housing
13 Guide carriage
14 Guide carriage top
surface
15a-b Sides
16a-c Roller axles
17a-b Outer rope guiding
rollers
17c Center rope guiding
roller
18 Rope direction
19 Rail guide
21 Rollers
22 Pivot axle
23 Support frame
24 Adjusting screw
Length
26 Link
