METHOD AND APPARATUS FOR PLASTIC IMPREGNATION AND JACKETING OF WIRE ROPES

APPAREIL SERVANT A IMPREGNER DE MATIERES PLASTIQUES DES CABLES METALLIQUES ET A LES ENROBER D'UN CHEMISAGE PLASTIQUE, ET METHODE CONNEXE

English Abstract

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Abstract of the Disclosure:
A method for single pass impregnation and jacketing of
a wire rope comprises the steps of injecting plastic material
in molten state into the wire rope under sufficient heat and
pressure to fill the interstices between at least the outer
strands of the rope, and directing the excess plastic
material from the surface of the filled wire rope at the exit
of the extrusion process to provide a jacket of plastic
material integrally formed with the filled wire rope. The
apparatus comprises an extruder for injecting the plastic
material into the wire rope and a die located at the exit end
of the extruder for removing the excess plastic material from
the surface of the filled rope and subsequently redirecting
it onto the surface of the wire rope to provide the jacket of
plastic material.

Claims

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CLAIMS
1. A method for single pass impregnation and
jacketing of a wire rope made of several outer strands
wound over inner strands comprising the steps of:
a) injecting plastic material in molten state
into the wire rope under sufficient heat and pressure to
fill the interstices between at least the outer stands of
the rope; and
b) removing the excess plastic material from
the surface of the wire rope and subsequently redirecting
said excess plastic material onto the surface of the wire
rope so as to provide a jacket of plastic material
integrally formed with the wire rope and concentric
thereto.
2. A method as defined in claim 1 wherein the
thickness of the jacket of plastic material is between
about 0.05 and 0.2 inch (1.25 and 5 mm).
3. A method as defined in claim 1, wherein the wire
rope is a lubricated, galvanized or essentially dry wire
rope.
4. An apparatus for single pass impregnation and
jacketing of a wire rope made of several outer strands
wound over inner strands comprising:
a) an extruder for injecting plastic material

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in molten state into the wire rope under sufficient heat
and pressure to fill the interstices between at least the
outer strands of the wire rope; and
b) a die located at the exit end of the
extruder for removing the excess plastic material from the
surface of the wire rope and subsequently redirecting said
excess plastic material onto the surface of the wire rope
so as to provide a jacket of plastic material which is
integral with the plastic material of the wire rope and
concentric thereto.
5. An apparatus as defined in claim 4, wherein the
jacketing die comprises an inside cavity, a scraper having
an inside diameter slightly larger than the outer diameter
of the wire rope mounted in said cavity for removing the
excess plastic material from the surface of the wire rope,
means for defining a passage between the scraper and the
wall of the cavity do direct the excess plastic material
onto the surface of the wire rope to form an integral
jacket of plastic material on the wire rope, and adjustment
means mounted on the jacketing die and engaging the
scraper to ensure that the jacket of plastic material is
concentric with the wire rope.

Description

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METHOD AND APPARATUS FOR PLASTIC IMPREGNATION AND JACKETING
OF WIR~ ROPES
This invention relates to a method and apparatus for
single pass impregnation and jacketing of wire ropes.
It is well known to impregnate wire ropes with plastic
material in order to decrease wear and ~Eatigue of the rope
and increase its life. Canadian Patent No. 1,208,863 issued
to the same interest as the present app:Lication discloses
such a plastic filled wire rope. It is often desir~ble in
some applications where a plastic filled wire rope does not
pass over shackles, pulleys or the like, such as in mine
shaft balanced ropes, to provide a jacket of plastic material
over the rope to prevent corrosion. This is normally done by
subsequently extruding a jacket of plastic material over the
plastic filled wlre rope. This operation has however never
been very satisfactory because the subsequently applied
jacket of plastic material does not adequately adhere to the
plastic filled wire rop72 and eventually peels of f .
It is the object of the present invention to provide a
jacket of plastic material which is integrally formed during
impregnation of the plastic material and there~ore forms part
of the plastic filled wire rope~
The method 7 in accordance with the present invention
comprises the steps of injecting plastic material in molten
state into the wire rope under sufflcient heat and pressure
;~ to fill the interstices between at least the outer strands o~
the rope, and directing the excess plastic material from the
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surface of the filled wire rope at the exit of the extrusion
process to form a jacket of plastic material integral with
the plastic material of the filled wire rope.
The thickness of the jacket of plastic material is
preferably between about 0.05 and 0.2 inch (1.25 and 5 mm)
depending on the diameter of the wire rope and its desired
~ properties.
; The apparatus for single pass imp:re~nation and jacket-
ing of the wire rope comprises an extruder for injecting
plastic material in molten state into the wire rope under
sufficient heat and pressure to fill the interstices between
at least the outer strands of the wire rope, and a die lo-
cated at the exit end of the extruder for removing the excess
; plastic material from the surface of the wire rope and subse-
quently redirecting it onto the surface o~ the wire rope to
: provide a jacket of plastic material integral with the plas-
~ tic material o~ the filled wire rope.
`~ The jacketing die preferably comprises a scraper having
an inner diameter slightly larger than the diameter of the
wire rope ~or removing the excess plastic material and means
. for subsequsntly redirecting the excess plastic material onto
the surface of the wire rope to form the jacket of plastic
. materlal.
The invention will now be disclosed, by way of example,
with reference to the accompanying drawings in which:
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Figure 1 is a longitudinal, generally cross-sectional
view of the extruder arrangement for carrying out the
preferred embodiment in accordance with the present inven~
tion;
Figure 2 is an enlarged cross-sec1ional view along line
2-2 of the jacketing die shown in Figure 1; and
: Figure 3 is a cross-sectional view of a plastic filled
wire rope made with the method in accordance with the inven-
tion.
Referring to Figures 1 and 2, preheated wire rope 10 is
passed through an extrusion cross-head ll. The preheating
operation has not been illustrated because it can be carried
out by any desired means, such as an induction heater, a
flame heater or the lik
;: 15 Molten plastic is typically supplied by an extruder
through passages 12, 13 and 14, as shown by the arrows. The
plastic is supplied under pressure which is generated by an
extrusion screw (not shown). The pressurized plastic
penetrates the rope lO between extrusion dies 16 and 17 and
the rearward flow of plastic through the rope pushes out any
excess lubricant 15 at the rear of die 16 and out of the
cross-head 11. Bulging of the excess plastic matsrial be-
tween the strands normally occurs as the filled rope exits
die 17. A jacketing die 18 is mounted on the exit end of die
- 25 17 for removlng such excess plastic material and redirecting
it onto the plastic filled wire~rope to form a jacket in-
te~ral with the plastic material of the plastic filled wire

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rope. The jacketing die comprises a scraper 19 having an in-
ner diameter slightly larger than the diameter of the wire
rope to remove the excess plastic mater:ial from the surface
of the wire rope. The scraper is mounted in an insid2 cavity
20 formed in the jacketing die and is centrally spaced in the
cavity by means of sp~cers 21 which define a passage between
the cavity and the scraper to allow forward flow of plastic
material onto the plastic filled wire rope. The scraper is
provided with adjustment screws 22 to Pnsure that the jacket
of plastic material is of even thickness around the wire
rope. It i5 to be understood that other means for removing
excess material from the surface of the wire rope and
redirecting so as to form a jacket integral with the plastic
filled wire rope are also envisaged within the scope of this
invention.
Figure 3 shows a cross-section of a typical filled wire
rope having 8 outer strands over 8 inner strands over a 6
strand IWRC (Independent Wire ~ope Core). This wire rope 23
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is essentially fully filled with pla~stic material 24 in the
interstices between the individual outer and inner strands
and ~urther comprises a jacket ha~ing a thickness between
about 0.05 and 0.20 inch integrally formed with the plastic
filled wire rope. With proper adjustment of the scraper 19,
the jacket is made concentric with the wire rope which means
that an uniform layer of plastic material is formed on the
wire rope for adequate protection of the wire rop~ against
~;~ corrosion. '
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Although the invention has been disclosed with
reference to a plastic filled lubricated wirs rope o~ the
type disclosed in Canadian Patent No. 1,208,863 referred
to above, it is to be understood that it may also apply to
any plastic filled wire rope whether it is lubricated,
galvanized or even dry. It is also to be understood that
the expression "wire rope" may mean either t,he final wire
rope product or a wire rope core around which further
strands may be wound to produce the final product. It is
quite common in the industry to use a wire rope as a core
in order to make a larger wire rope product. In this case
the jacket around the wire rope core will act as a cushion
for the surrounding ~trands and thereby will extend the
life of the fi~al ~1re rope product.
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Representative Drawing