TECHNICAL FIELD
[0001] The present invention relates to a rope usable for an elevator and mechanical handling
equipment.
[0002] In an elevator, a cage and a balance weight are connected to each other by a rope,
and the rope is driven by a frictional force generated between a sheave of a hoisting
device and the rope extending around the sheave. On the other hand, in a winding drum
type elevator or a mechanical handling equipment, a rope for suspending a load is
wound on a winding drum to be driven.
[0003] A conventional rope usable in these conventional mechanisms has a structure in which
a fabric rope impregnated with lubricant oil is positioned as a core at a center of
the rope, and constitutes each of which includes twisted steel wires are twisted around
the fabric rope. When the rope is used on a small diameter sheave or pulley, a life
duration of the rope is significantly decreased by fatigue and abrasion of the wires
caused by flexure of the rope. Further, since a frictional coefficient between the
sheave and the rope is small, the smaller a diameter of the sheave is, the greater
a difficulty of securely maintaining a driving frictional force is.
[0004] Therefore, a diameter of the sheave for frictional driving is not less than forty
times of a diameter of the rope. That is, a driving torque is increased by an increase
of the diameter of the sheave so that a size of a driving device is increased. Conventionally,
the elevator is designed to satisfy the increased driving torque, but a demand for
decreasing a size of an element device increases in accordance with an increase in
demand for decreasing a space for the elevator.
[0005] For this demand, a new rope capable of decreasing the diameter of the sheave for
the rope is proposed. For example, JP-A-07-267534 proposes that organic filaments
are used as a load bearing member, and since each of the filaments has a diameter
not less than 10µm and less than 20µm, a fatigue of the load bearing member does not
occur and a longer lasting life of the rope is obtainable even when a curvature radius
of the rope is decreased.
[0006] Further, in JP-A-3-82883, a rope in which a lubricating protect layer is attached
to each of bundles of twisted wires, the bundles of twisted wires are twisted, and
an outer periphery of the twisted bundles is coated is proposed.
DISCLOSURE OF THE INVENTION
[0007] In the above proposes ropes, since a modulus of longitudinal elasticity of the load
bearing member is smaller than that of the conventional wire ropes, a longitudinal
rigidity of the rope is small. Therefore, a cargo is apt to oscillate remarkably when
a length of the rope is long. Further, since the rope is of organic material, the
rope has a low thermostability, and is apt to have aged deterioration. Further, when
the rope is repeatedly bent on the small diameter sheave, an abrasion occurs between
the wires and a life of the rope is decreased by a fatigue caused by a repeated stress
application. Further, a frictional coefficient between the rope and the sheave is
small to cause a slip so that a great driving force cannot be transmitted.
[0008] According to the present invention, these conventional drawbacks are overcome to
obtain a soft and long-life rope with preferable frictional coefficient.
[0009] A rope of the invention is configured in such a manner that a core is a first coated
constitute in which a first constitute as a twisted bundle of metallic wires is coated
with a coating material, an annular bundle of second coated constitutes in each of
which a second constitute as a twisted bundle of metallic wires is coated with the
coating material is twisted on a periphery of the core, and a periphery of the annular
bundle of second coated constitutes surrounding the first coated constitute is coated
with a third coating material so that the second and third coating material are joined
to each other.
[0010] In this case, "join" means an adhesion by an adhesive, a fusion bonding between two
members by heating, a bonding by chemical treatment and so forth.
[0011] Since each of the first and second constitutes is the twisted bundle of metallic
wires, the rope has a high rigidity and a low aged deterioration, and since each of
the first and second constitutes is coated with the coating material, the wires of
the first and second constitutes are prevented from directly contacting each other
and from slipping with respect to each other, so that a high-abrasion-resistant and
long-life rope is obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012]
Fig. 1 is an overall view showing an embodiment of an elevator to which a rope of
the invention is applied.
Fig. 2 is a cross sectional view showing a rope as an embodiment of the invention.
Fig. 3 is a cross sectional view showing an embodiment of a coated structure forming
the rope of Fig. 2.
Fig. 4 is a cross sectional view showing another embodiment of the coated structure
forming the rope of Fig. 2.
Fig. 5 is a cross sectional view showing an embodiment of a coated structure forming
the rope of Fig. 2.
Fig. 6 is a cross sectional view showing an embodiment of a coated structure forming
the rope of Fig. 2.
Fig. 7 is a cross sectional view showing a rope as another embodiment of the invention.
Fig. 8 is a cross sectional view showing a rope as another embodiment of the invention.
Fig. 9 is a detailed cross sectional view of the rope shown in Fig. 2.
Fig. 10 is a detailed cross sectional view of the rope shown in Fig. 6.
Fig. 11 is a detailed cross sectional view of the rope shown in Fig. 7.
Fig. 12 is a cross sectional view showing a rope as another embodiment of the invention.
BEST MODE FOR BRINGING THE INVENTION INTO EFFECT
[0013] Fig. 1 is an overall view showing an embodiment of an elevator to which a rope of
the invention is applied.
[0014] In Fig. 1, a carrier cargo 1 for a passenger or freight includes at lower part thereof
pulleys 5a and 5b for receiving a rope 10, and a balance weight 2 balancing approximately
with a total amount in weight of the carrier cargo 1 and a half of a rated load thereof
includes an upper part thereof a pulley 5e for receiving the rope 10.
[0015] Pulleys 5c and 5d for receiving the rope 10 are arranged at a top of a hoistway 7,
and a driving device 3 including a sheave 3a is arranged at a lower part of the hoistway
7. The rope 10 of the invention extends from a rope catcher 6a through the pulleys
5a and 5b below the carrier cargo and the pulley 5c on the top to the sheave 3a of
the driving device 3 to partially surround it. Further, the rope passes the pulley
5d on the top and the pulley 5e of the balance weight and terminates at a rope catcher
6b at the top.
[0016] Since the rope 10 of the invention is soft and has a great frictional coefficient
between its coating and the sheave 3a, the rope is usable in a long life and capable
of securely transmitting a driving force even when a sheave diameter is small. For
example, the sheave diameter may be from one-third to one half of the conventional
sheave diameter. Therefore, since a driving torque to be generated by the driving
device may be from one-third to one half, a size of the driving device can be significantly
decreased. Further, since diameters of the pulleys below the carrier cargo, on the
upper part of the balance weight and at the top of the hoistway may be small similarly,
an overhead (a distance between a surface of an uppermost floor and a ceiling of the
hoistway) and a pit depth (a distance of a surface of a lowermost floor and a pit
of the hoist way) can be decreased.
[0017] Figs. 2-9 are cross sectional views showing the ropes of the invention. The rope
is formed by a first coated constitute 12 arranged at a center of the rope and a plurality
of second coated constitutes 13 arranged around the first coated constitute 12 while
the first and second coated constitutes 12 and 13 are twisted and a coating (outer
coating) 11 is formed on an outer periphery of the twisted first and second coated
constitutes. Each of the coated constitutes 12 and 13 is formed by high-tension steel
wires each of whose diameters is from one hundredth to one fifteenth of a diameter
of the rope without the outer coating and by forming a coating (inner coating) on
each bundle of the small diameter wires. The small diameter wires enable the rope
to be softened and to extend easily around the small diameter sheave and pulley.
[0018] The coating (inner coating) of the coated constitutes 12 and 13 is made of an organic
(thermoplastic) material being adhesive to the wires and having a preferable elasticity,
and the coating (outer coating) of the rope is made of an organic (thermoplastic)
material having a preferable frictional coefficient with respect to the sheave and
being abrasion-resistant.
[0019] Since the rope is formed by twisting the second coated constitutes 13 around the
first coated constitute 12 and a difference in curvature radius among the first and
second coated constitutes 12 and 13 is generated when the coated rope is bent repeatedly,
a mutual slip among the constitutes occurs.
[0020] Further, since the coated constitutes are twisted, a pressing force is generated
between the coated constitutes when a tension is applied to the coated rope, and a
radial pressing force is generated in the rope when the rope extends around the sheave
and pulleys. As described above in an actual operating condition, the pressure and
mutual slip are generated between the coated constitutes.
[0021] Therefore, if the constitutes 12 and 13 have no coating, the wires contact each other
directly so that an abrasion of the wires occurs. Since diameters of the wires are
decreased to soften the rope, an operating life of the rope is significantly decreased.
The coatings on the constitutes 12 and 13 prevent the direct contact of the wires
between the constitutes. That is, by the coating between the wires of the constitutes
adjacent to each other, the direct contact of the wires therebetween is prevented
so that the abrasion of the wires is restrained. On the other hand, although the pressure
and mutual slip are generated between the coatings of the constitutes adjacent to
each other, the pressure and mutual slip are lightened by an elasticity of the coatings,
and the abrasion resistance is significantly improved.
[0022] The coating applied to the constitute is effective for lightening the pressure and
mutual slip between the constitutes adjacent to each other. It is desirable for increasing
this affect to increase a thickness of the coating. On the other hand, if the thickness
of the coating is needlessly great, a ratio of a cross sectional area of a load bearing
member to a cross sectional area of the constitute becomes small. In this case, a
ratio of the load bearing member to a cross sectional area of the rope formed by twisting
the constitutes becomes small so that the cross sectional area needs to be great for
keeping the strength unchanged. Therefore, the thickness of the coating is made as
small as possible as a minimum thickness necessary for lightening the pressure between
the wires and the mutual slip, for example, preferably 0.2-0.5 mm.
[0023] A gap δ is formed between the second coated constitutes 13 adjacent to each other
around the first coated constitute 12 so that the coating material forming the outer
coating can easily permeate between the constitutes. Therefore, not only a contact
area between the outer coating 11 and the second coated constitutes 13 but also a
contact area between the outer coating 11 and the first coated constitute 12 are increased
so that an adhesive strength or fusion bonding strength between the inner and outer
coatings is improved.
[0024] Fig. 3 shows a concrete structure of the coated constitute 12 or 13. A constitute
22 is formed by twisting wires 21, and an outer periphery thereof is coated with a
coating 23 to form a coated constitute 20. In this case, diameters of the wires 21
is, as described above, from one thirteenth to one hundredth of the diameter of the
rope without the outer coating. In this embodiment, the constitute has (1+6+12) structure
(double layer windings) by 19 wires extending parallel to each other. In this structure,
a line contact is formed between the wires so that a contact pressure between the
wires generated by longitudinal and radial loads applied to the rope is lightened
in comparison with a point contact therebetween. Since diameters of the wires of the
constitute 11 is small, a mutual slip length between the wires in the constitute when
generating the flexure of the rope becomes small. Therefore, a product of the pressure
and the slip length (so called PV value) determining an abrasion amount of the wire
is made small to restrain the abrasion of the wires. Further, since the diameter of
the wires is small, a fatigue of the wires caused by bending the rope is restrained.
[0025] When the coating 23 is formed on the constitute 22 formed by twisting the wires 21,
the constitute 22 is cleaned by a cleaner, and subsequently the coating 23 is formed
after coating the constitute 22 with an adhesive or the surfaces of the wires and
the coating material are chemically bonded to each other by forming the coating after
performing a suitable subsequently surface treatment on the wires. For example, the
wires are plated with brass, and the coating including sulfur is formed on the constitute
22 so that the plating component on the surface of the wires and a component of the
coating material are chemically bonded to each other by vulcanization.
[0026] The wires positioned on the outer periphery of the constitute 22 and the coating
are adhered to each other to be held, and the wires positioned at the inside of the
outer periphery are not restrained from moving. Therefore, a resistance is small when
being bent to a small curvature radius, so that the soft rope is obtainable. In this
case, since the wires directly contact each other extend parallel to each other and
the diameter of the wires are small, the contact area is great so that the surface
pressure is small and the slip between the wires generated when bending the rope is
significantly small, so that a longer lasting life is obtainable.
[0027] Fig. 4 shows another embodiment of the first or second coated constitute 12 or 13.
The same reference numeral denotes the same member. If a relatively great strength
of the rope is required, a number of the wires needs to be increased because a diameter
of the wires is small. In this embodiment for such requirement, the constitute has
(1+6+12+18) structure (triple winding layers) by 37 twisted wires. When the number
of the wires increases, as shown in Fig. 3, it is difficult for the wires to be twisted
with a constant pitch between the wires.
[0028] Fig. 4 shows that a pitch between the wires is changed in accordance with a change
in winding layers so that a cross sectional shape is easily kept circular. Although
Fig. 3 shows the wires extending parallel to each other with a cross angle of zero
therebetween, this embodiment cannot have the cross angle of zero because the pitch
between the wires is changed in accordance with the change in winding layers. However,
since the change in the pitch between the winding layers is small, the cross angle
is small so that the length of contact line between the wires can be kept great to
improve the abrasion resistance of the wires.
[0029] Even if the number of the wires needs to be increased further, the similar constitute
enables the cross sectional shape to be kept circular and the improvement of the abrasion
resistance. This improved productivity is effective for decreasing a cost of the produced
rope.
[0030] Fig. 5 shows an embodiment of a coated constitute 30 in which a further increased
number of the twisted wires is required. Similarly to the above described constitute
22 (Fig. 3), a constitute 32 includes a central constitute 35 formed by twisted wires
31, and seven constitutes 34 which has a structure similar to the central constitute
35 and whose annular bundle is twisted around the central constitute 35, and an outer
periphery of the constitute 32 is coated with a coating 33 to form a coated constitute
30. That is, the coated constitute 30 is formed by twisting seven of the constitutes
22 shown in Fig. 3 to form the constitute 32 and coating the outer periphery thereof.
Although this embodiment has the seven of the constitutes 22 shown in Fig. 3, this
limitation is not absolute.
[0031] Since the wires of the central constitute 35 and the wires of the circumferential
constitutes 34 directly contact mutually in this structure, the abrasion resistance
of the wires of this structure is inferior to that of the above described structures
(Fig. 3 and 4), however, this structure is soft suitably for an requirement of the
high tension rope. Further, even though the wires of the circumferential constitutes
34 directly contact, because of a short distance thereof from a center of the central
constitute 35, a length of mutual slip between the wires is small so that the abrasion
is restrained. Therefore, this structure is preferable for being applied to the core
constitute 12 having a short distance from a rope center.
[0032] In Figs. 6 and 10, seven of the coated constitutes 20 formed by coating the constitutes
22 are twisted. That is, a constitute 42 is formed by twisting constitutes 41, and
an outer periphery of the constitute 42 is coated with a coating 43 to form a constitute
40. In this structure, the wire contact is prevented between the constitutes 41 adjacent
to each other so that the abrasion resistance of the wires is significantly improved.
On the other hand, a ratio of the load bearing member to the cross sectional area
of the rope is decreased by a cross sectional area of the coating on the constitutes
41 so that a strength per unit cross sectional area is decreased. Therefore, a thickness
of the coating is made as small as possible to a minimum thickness for lightening
the pressure and mutual slip between the wires. This structure is chosen in view of
a balance among the strength, size and operating life of the coated rope.
[0033] In Figs. 7 and 11, another embodiment of the rope is shown. This structure is basically
similar to the embodiment of Fig. 2 while this structure has the core coated constitute
12, eight of the coated constitutes 13 twisted around the core coated constitute 12,
and the coating 11 on the outer periphery of the coated constitutes 13. The core coated
constitute 12 and coated constitutes 13 are similar to those of Fig. 2 respectively.
[0034] Fig. 8 shows another embodiment in which constitutes 51 are twisted to form a constitute
52, and the constitute 52 is coated with a coating 53 to form a constitute 50 so that
the rope is formed. The rope of this structure is not restrictive on being designed
in comparison with the above described ropes so that an acceptable range on design
choice is expanded. That is, in the above described ropes, diameters of the core coated
constitute and the circumferential constitutes around the core is limitative for increasing
the cross sectional area of the load bearing member in the cross sectional area of
the rope, that is, a ratio of a total amount of the cross sectional areas of the wires
to the cross sectional area of the rope. On the other hand, in this embodiment, the
constitutes may have a common diameter, so that the diameter of the wires, the diameter
of the constitutes and the diameter of the rope can be freely designed and the rope
can be easily produced.
[0035] Fig. 12 shows another embodiment. This is basically similar to the embodiment of
Fig. 7, but the core coated constitute is formed by twisting the wires 21 around a
core steel 24. In this embodiment, the coated constitute can have a great diameter
as desired without increasing significantly the number of the wires.
[0036] For keeping a longitudinal rigidity of the produced rope, the wires and/or the coated
constitutes are twisted while applying an appropriate tension thereto in a process
of forming the constitute by twisting the wires and/or a process of forming the rope
by twisting the coated constitutes. By this, an unnecessary space is eliminated between
the wires or the coated constitutes so that an elongation of the rope can be restricted
when the tension is applied to the produced rope.
[0037] When the constitute formed by twisting the wires is coated, an effective adhesive
force does not occur between the wires and the coating material. For obtaining the
effective adhesive force, the constitute is cleaned, an adhesive is applied to the
constitute after evaporating a solvent medium of a cleaner, and the coating (inner
coating) is formed with the organic coating material during an extrusion molding process
while pulling out the constitutes. The coated constitutes are twisted to form the
rope while applying the tension to the coated constitutes, and subsequently the outer
periphery of the twisted coated constitutes is coated with the organic coating material
(outer coating). By heating previously the rope of the twisted coated constitutes
to a certain temperature, the inner and outer coating are joined each other with fusion
bonding when the outer coating is formed. Therefore, when the driving force is transmitted
from the sheave, the driving force is transmitted from the outer coating through the
inner coating to the constitutes (load bearing member), so that the driving force
is transmitted without slip between the inner and outer coatings or between the inner
coating and the constitutes to drive the carrier cargo.
[0038] As an alternate for adhering the coating to the constitute, a chemical bonding in
which a surface treatment is performed on the wires, and subsequently a constituent
of the coating material for covering the wires and a constituent of the treated surface
of the wires are made react chemically each other is usable to bond the wires and
the coating each other. A bonding strength by this chemical reaction is greater than
an adhesion strength.
[0039] A purpose of the inner coating is to prevent the wires of the constitutes adjacent
to each other from contacting other, and a thickness of the inner coating is preferably
as small as possible to increase the ratio of the cross sectional area of the load
bearing member to the cross sectional area of the rope so that a small-diameter and
high-strength rope is obtainable while achieving the purpose. Therefore, the thickness
is preferably 0.2-0.5 mm. A purpose of the outer coating is to transmit the driving
force from the sheave to the load bearing member of the rope while an abrasion thereof
is kept small for a long time period against the contact with the sheave, and the
thickness of the outer coating needs to be sufficient against the abrasion. Therefore,
the thickness of the outer coating is preferably 0.5-1.0 mm with taking into consideration
various conditions in which the rope is used.
[0040] In the rope as the embodiments of the invention, since the small diameter metallic
wires are used, the rigidity is high and the aged deterioration is prevented, while
the flexibility is superior and an excessive force is prevented from being applied
to the load bearing member around the small diameter sheave. Further, since the rope
is formed by twisting the coated constitutes each of which is formed by coating twisted
metallic wires, the wires are prevented from contacting each other and slipping between
the constitutes, the abrasion resistance and long life are obtainable.
[0041] Further, since the rope is formed by coating the coated constitutes after being twisted,
the frictional coefficient with respect to the sheave is appropriately set, and the
abrasion of the inner coating and wires is prevented. Since the coating covering the
constitute and the coating covering the rope are individual with respect to each other
to form a double layered coating, each of the coatings can be made of an optimum material
for its necessary performance, a permissible range for design choice is increased,
and a productivity is improved.
[0042] Further, since the wires are adhered to the inner coating, the slip between the wires
and the inner coating is prevented so that the abrasion of the inner coating is prevented,
and the operating life of the rope can be extended.
[0043] Further, Since the rope of the invention can have an appropriate frictional coefficient
on the sheave even and the long operating life when the sheave has a small diameter,
the driving device and the element attached thereto, for example, the pulley can be
made small. Therefore, the elevator can has a compact size and a long cycle time period
of replacing the rope. Consequently, an initial cost and maintenance cost of the elevator
can be decreased.
INDUSTRIAL APPLICABILITY
[0044] According to the present invention, since the metallic wires are twisted, the rope
has a high rigidity and small aged deterioration, and since the rope is coated with
the coating member, the rope has a long operating life and a superior abrasion resistance
without the direct contact and slip between the wires.
1. A rope comprising a first coated constitute in which a first constitute of twisted
metallic wires is coated with a first coating member, second coated constitutes in
each of which a second constitute of twisted metallic wires is coated with'a second
coating member, and a third coating member with which an outer periphery of the second
coated constitutes surrounding the first coated constitute is coated, characterized in that the second and third coating members are capable of being joined each other.
2. A rope according to claim 1, characterized in that the first and second constitutes have strand structure in which the wires are twisted
or Schenkel structure in which strands each of which is formed by twisting the wires
are twisted.
3. A rope according to claim 1, characterized in that the first and second constitutes are formed of elastic organic material.
4. A rope according to claim 1, characterized in that the second coating members are formed of an inner coating material capable of being
joined with the second constitutes, and the third coating member is formed of an outer
coating material capable of having an appropriate frictional coefficient with respect
to a sheave.
5. A rope according to claim 1, characterized in that thicknesses of the first and second coating members are 0.2-0.5 mm.
6. A rope according to claim 1, characterized in that second and third coating members are joined by fusion bonding, adhesive or chemical
bonding.
7. A rope according to claim 1, characterized in that the second coating member and the metallic wires of the second constitutes are bonded.
8. A rope according to claim 7, characterized in that the second coating member and the metallic wires of the second constitutes are bonded
by adhesive or chemical bonding.
9. A rope comprising a first coated constitute in which a first constitute of twisted
metallic wires is coated with a first coating member, second coated constitutes in
each of which a second constitute of twisted metallic wires is coated with a second
coating member, and a third coating member with which an outer periphery of the second
coated constitutes surrounding the first coated constitute is coated, characterized in that the second coating member and the metallic wires of the second constitutes are bonded.
10. A rope according to claim 9, characterized in that the second coating member and the metallic wires of the second constitutes are bonded
by adhesive or chemical bonding.