Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
_
Field of the Invention
This invention relates to a filler-laid wire rope.
Descripti~n of the Prio~ Art
In the fabrication of a w~re core rope, it is known
in the art to fill the gaps between the individual outer strands
with a filler material like a thermoplastic resin or to
impregnate a filler material into all the gaps and interstices
including the gaps between the core rope and the outer strands
as disclosed in U.S. Patent No. 3,824,777. Such impregnated wire
ropes possess excellent properties in abrasive resistance, fati-
gue strength and loss of wire rope breaking load by stranding
and closing, due to the effects of suppressing abrasive contact
of the individual outer strands or of the outer strands with the
core rope and entrapping the lubricant oil impregnated into the
core rope and strands. However, the conventional impregnated
wire rope which has the filler material integrally positioned
around its entire outer periphery has an inherent drawback in
that the flexibility of the wire rope as a whole is impaired
to a considerable degree. Further, the filler material is
susceptible to cracking and peeling especially when the rope is
used as a running rope.
SUMMAR~ OF THE INVENTION
- . . .
Therefore, the present invention has as its object
the provisi~n for a wire rope which does not invite deterioration
in flexibility and prevents cracking and peeling of the filler
material, while retaining the fundamental effects with regard to
the higher abrasive resistance and fatigue strength and reduction
of loss of wire rope breaking load by stranding and closing.
One feature of the wire rope according to the present
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1 invention resides in the fact that, in filling a filler material
in the interstices between the core rope and the respective outer
strands and/or in the gaps between the individual outer strands,
a filler element is placed independently in the respective inter-
stices and gaps qr an interstice and an outwardly contiguous
strand gap are treated ~s an independent unit.
Another feature of the invention resides in the fact
that a reinforcing core is anchored in the filler element
at least in the interstices between the core rope and the
respective outer strands.
~RIEF DESCRIPTION OF THE DRAWINGS
Various other objects, features and attendant advan-
tages of the present invention will be more fully appreciated
as the same becomes better understood from the following detailed
description when considered in connnection with the accompanying
drawinys in which like reference characters designate like or
corresponding parts through the several views and wherein:
Fig. 1 is an enlarged sectional view o a wire rope
in accordance with a first embodiment in the present invention;
Fig. 2 is a fragmentary perspective view of a filler
element;
Fig. 3 is a schematic view showing filler elements of
different sectional shapes;
Fig. 4 shows an apparatus for producing the wire rope
of the present invention;
Fig. 5 is an enlarged sectional view taken along line
V-V of Fig. 4;
Fig. 6 is an enlarged view showing a wire rope con-
struction in accordance with a second embodiment,
Fig. 7 is a fragmentary perspective view of the filler
elements used in the second embodiment;
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1 Fig. 8 is an enlarged section~l view.showing a third
embodiment o$ the present invention; and
Fig. 9 is a fragmentary perspective view of the filler
elements us.ed in the third embodiment.
DETAILED DESC~I;PTION OF THE PREFER~ED EMBODI~NTS
First of all, it is to be.understood that the present
invention is applicable to wire ropes in general irrespective
of the wire rope core, strand core and fibre core. By way of
example, the following description shows a wire rope with a wire
rope core, more specifically, IWRC 6 x Fi(25) JIS Type 14.
Referring to Fig. 1, designated by reference number
1 is a core rope, by 2 six outer strands arranged around the
outer periphery of core rope l, and by 3 a filler element which
fills independently each one of the interstices a which are formed
between core rope 1 and outer strands 2. Filler element 3 of a
thermoplastic resin or the like is formed into a cord-like shape
substantially of triangular cross-section in con~ormity with the
interstice a, as shown in Fig. 2, and laid together with core
rope 1 and outer strands 2 at the time of closing the rope to
fill the respective interstices a independently of each other like
outer strands 2. In this instance, iller elements 3 are pre-
ferably formed slightly larger than the cross-section of the
interstices a. By so doing, filler elements 3 are securely con-
tacted with core rope 1 and outer strands 2 by the closing
pressure, enhancing the efects o the iller elements all the
more, namely, the effect of separating core rope 1 and outer
strands 2 from each other and the effect of sealing the lubricant
oil (not shown) which is impregnated between core rope 1 and
outer strands 2.
The outer strands of the wire rope are arranged to
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1 have a percentage of voids in the range of 2,0 - 6.0%, The
grounds for this definition of the value of the percentage of
voids h are shown below,
circumference of sum o~ arc AB
~ercentage pitch circle of wire rope - (= 6 ~)
of voids h = (= 2~) x 100
(%) 2~y
10 ~
When a wire rope which has a percentage of voids greater
than about 2% is bent on a sheave, it is possible to avoid con-
tacts of the strands on the inner side (compression side) of
the bend. This is the reason why the minimum value of the pQr-
centage of voids h is set at 2.0%. On the other hand, if the
percentage of voids h exceeds 6.0~, the core rope is exposed
to an external view, lowering the commercial value of the wire
rope. In addition, a percentage of voids greater than 6% in-
variably requires reduction in the diameter of the outer strands,
making it difficult to guarantee the standard breaking load.
Thus, the maximum value of the percentage of voids h is 6.0%.
Accordingly, in the present invention, the filler elements 3 are
laid with a precondition that the percentage of voids h is 2.0
to 6,0%.
It is preferred to anchor a reinforcing core 4 of a
30 wire or hemp centrally in respective filler elements 3.
--4--
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1 Reinforcing core 4 contributes to strengthen filler elements
3 and to prevent its cracking or peeling especially when in
ser~ice as a running rope, while improving the breaking
characteristics of the wsre rope as a whole. Further, it also
has an effect of preventing the filler element from rupturing,
falling or twisting during the clos-ing operation.
In addition to the shapes shown in Figs. 1 and 2, it
is possible to form filler elements 3 in various other shapes as
shown in Fig. 3. According to the present inventionj such is
formed into a suitable shape which conforms to the interstice a.
The above-described filler-laid wire rope is fabricated
by the method and apparatus as follows. Referring to Figs. 4
and 5, indicated by reference number S is a feeder for core rope
1, by 6 bobbins for the outer strands 2 and filler elements 3,
by 7 a guide plate, by 8 a closing die, by 9 an oil feed tank,
by 10 capstans and by 11 and take-up reel. Guide plate 7 is
provided with a core rope passing hole 7a at the center thereof,
filling passing holes 7b formed in positions radially outward
of the core rope passing hole 7a, and outer strand passing
holes 7c formed in positions radially outward of filler passing
holes 7b. Filler passing holes 7b are preferably formed sub-
stantially in the same shape as filler element 3 to guide the
latter in a correct posture. Core rope 1 and filler elements
3 which are supplied from feeder S and bobbins 6 are passed
through respective holes 7a and 7b of guide plate 7 and thereby
held in predetermined positional relationship before being
intertwisted by closing die 8. The filler-laid wire rope of
Fig. 1 is thus produced and taken up on reel 11. Thus, the
wire rope of the invention can be produced easily fundamentally
by the conventional wire rope fabricating method and apparatus,
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t maintaining core rope 1, outer strands 2 and filler elements
3 in predeterminea positional relationship ~y guide plate 7.
With the wire rope of the invent;on~ it is possi~le
to lessen considerably the contact pressure as caused between
core rope 1 and the respective outer strands 2 by a dynamic
load especially during service as a running rope, thereby
reducing abrasion and fatigue of core rope 1 and outer strands
2 as well as the loss of wire rope breaking load by stranding
and closing. Further, filler elements 3 seal in and prevent
exudation of the lubricant oil which is impregnated into core
rope 1 and outer strands 2. Consequently, the abrasive resist-
ance and fatigue strength of the wire rope as a whole are im-
proved while reducing the loss of wire rope breaking load by
stranding and closing. F~rthermore, the entrapped lubricant
oil lessens the necessity for relubrication when the wire rope
is in service and has the effect of preventing internal corrosion
over a long period of time.
In addition to the above-mentioned fundamental effects,
filler element 3 has another advantage in that no possibility
~0 exists of impairing the flexibility of the wire rope as a whole
since the filler element is laid independently ahd thus structur-
ally separately in the respective interstice a. Besides, as
mentioned hereinbefore, reinforcing core 4 protects the filler
element against damage, i.e. rupturing or peeling, to ensure
the àbove-mentioned effects of the filler elements for a re-
Iatively long period of time.
Illustrated in Figs, 6-9 are second and third em-
bodiments of the wire rope according to the present invention.
In the wire rope of Fig, 6, in addition to the filler elements
3 which are laid in the interstices a between core rope 1 and
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1 outer strands 2 in the same ~anner as in the foregoing embodiment,
filler elements 3' o~ a shape ~itting to the outer strand gaps
b (filler elements 3 and 3' are hereinafter referred to as "inner
filler element'l and "outer filler element", respectively) are
laid independently in the outer strand gaps b, In the wire
rope construction of Fig. 8, inner and outer filler elements
3 and 3' which are formed into an integral body as shown par-
ticularly in Fig. 9 are laid in each interstice a and an outwardly
contiguous outer strand gap b, treating the interstice a and the
contiguous gap b as an independent unit.
The wire ropes shown in Figs~ 6, and 8 lessens not
only the contact pressure between core rope 1 and outer strands
2 but also the contact pressure between the individual outer
strands 2, improving the wire rope as a whole in abrasive
resistance, fatigue stre~gth and loss of wire rope breaking
load by stranding and closing. Particularly, these effects are
manifested more pronouncedly in the wire rope construction of
Fig. 8 in which the outer strands 2 are completely separated by
' the bridge portions of the inner and outer filler elements 3 and
3'. These wire ropes also give excellent results in the effect
of entrapping the lubricant oil.
The wir,e rope construction of Fig, 6 provides sub-
stantially the same effect as in the embodiment of Fig. 8 if
inner and outer filler elements 3 and 3' are arranged to contact
with each other in the radial direction. In the wire rope
constructions of Fig. 6 and 8, the effect of entrapping the
lubricant oil i's augmented by contacting the adjacent outer '
filler elements 3' with each other through circumferentially
extending film portions in such a manner that the outer peri-
pheries of outer strands 2 are covered by,the contacting film
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1 portions. On the other hand, although the reinforcing cores 4are anchored in both the inner and outer filler elements in
these wire rope constructions, they may be embedded basically
only in inner filler elements 3 except for a special application
or a case where increased effects of the filler elements are
desired.
The foregoing wire ropes are also fabricated by laying
the filler elements concurrently with the outer strands at the
time of closing in the same manner as in the wire rope construction
of Fig. 1. Needless to say, the resulting wire ropes also have
the effects unique to the present invention, namely, retaining
flexibility and preventing cracking or peeling of the filler
elements, similarly to the wire rope construction of Fig. 1.
In the above-described concurrent filler-laying method
which has been employed for the fabrication of the wire rope of
the invention, the filler elements are laid in simultaneously
with the closing operation so that there is no need for providing
a separate filler-laying stage in the fabrication process, thus
ensuring high production efficiency of the rope. The method also
has advantages over the conventional coating method since it does
not require the preheating treatment of the rope prior to impreg-
nation of the filler material nor equipment like an extruder.
The low equipment cost, coupled with the high productivity of
the rope, permits realization of a material cost reduction of
the wire rope. ~n view of these points, the simultaneous filler-
laying method is considered to be the most advantageous and suit-
able method for the fabrication of the wire rope of the present
invention and thus to be the sole method which is conceivable
for actual application. However, any other method may be
employed as long as the filler elements can be laid in the same
manner.
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The following experiments more particularly illustrate
the fatigue strength and other properties of the wire rope ac-
cording to the present invention.
(Experiment 1)
The following wire rope specimens of IWRC 6 x Fi(25)
16 mm JIS Type 14 were subjected to a repeated bending test.
(i) A black wire rope;
(ii) A wire rope construction of Fig. 1 according to the
invention; and
(iii) A conventional wire rope having interstices and
gaps completely and integrally impregnated and
filled with a thermoplastic resin.
In the test, a pair of testing sheaves were positioned
between a drive sheave and a tension sheave and specimens (i) to
~iii) were passed in S-shape through the testing sheaves, fixing
their opposite ends to the drive and tension sheaves through
auxiliary ropes. A horizontal tensile load was applied to the
tension sheave during repeated bending tests under the following
conditions .
Rope diameter d (mm): 16
Testing sheave pitch diameter
D (mm): 256
D/d ratio: 16
Testing load (kg): 1190
Nominal breaking load of test
wire rope ~kg): 11900
Safety factor: 10
Sheave arrangement: S-shape
The test results are shown in Table 1.
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1 Ta~le 1
.. _
Specimens Number of repeated bendings (times) _
Initial wire 10% wire breaking
breakina (terminal point of test)
_
(i) 8500 17000
(ii) 12500 26500
(iii) 13000 27500
(Experiment 2)
The following wire rope specimens of n~Rc 6 x Fi(29)
44 mm were tested for flexibility, increase in diameter
and loss of wire rope breaking load by stranding and closing.
The test results are shown in Table 2.
~i) A black wire rope;
(ii) A wire rope construction of Fig. 1 according to
the invention; and
~iii) A conventional wire rope having interstices and
gaps completely and integrally impregnated and
filled with a thermoplastic resin.
Table 2
,
Flexi- Ro e diameter Loss of
jspecimens bility P Increment breaking load ,
(i) 100 44.80 O 18.1~23.1
45.46~45.58 +1.47_+1.74
~ii) 95flOO 46.26 46.38 +3.26~~3.5 14.1~18.1
~iii) 70f75 14.5~19.0
The flexibility is expressed by an index number based
on 100% of the black rope (specimen (i)), and the loss of wire
breaking load by stranding and closing is expressed by:
-- 10 --
~ 1~3~7g
1 ~oss of breaking
load (%) = (l- actual ~reaking lo-ad of wire rope 0
aggregate breaking load of ) x l0
- individual wires
The results of Experiments l and 2 show that the wire
rope of the present invention is almost comparable to the com-
pletely impregnated wire rope with regard to the repeated bending
strength in spite of the fact that the tested specimen was of
the construction of Fig. l with the filler elements laid only
in the inner interstices, and excels the latter in the
flexibility and loss of wire rope breaking load as well as the
increment in diameter.
It will be appreciated from the foregoing description
that the wire rope of the present invention retains the improved
properties of the impregnated wire rope in abrasive resistance,
fatigue strength and loss of wire rope breaking load by stranding
and closing, without impairing the flexibility of the wire
rope, while preventing cracking and peeling of the filler
material, and thus has an extremely high practical use character-
istic.
Obviously, numerous modifications and variations of
the present invention are possible in light of the above teachings.
It is therefore to be understood that within the scope of the
appended claims, the invention may be practiced otherwise than
as specifically described herein.
