EP1426482B1

EP1426482B1 - Rope

Info

Publication number: EP1426482B1
Application number: EP02749376.6A
Authority: EP
Inventors: I. Hitachi Mito Engineering Co. Ltd. Nakamura; A. Building Systems of HITACHI LTD. OMIYA; S. Mech. Eng. Res. Lab. of Hitachi Ltd IWAKURA; M. Cent.Res.Lab. Tokyo Rope Mfg. Co. Ltd KUSUDA
Original assignee: Hitachi Ltd; Tokyo Rope Manufacturing Co Ltd
Current assignee: Hitachi Ltd
Priority date: 2001-09-12
Filing date: 2002-07-26
Publication date: 2016-07-06
Anticipated expiration: 2022-07-26
Also published as: KR20040025933A; KR100611272B1; EP1426482B8; CN100393937C; JP4096879B2; JPWO2003025278A1; WO2003025278A1; EP1426482A1; EP1426482A4; CN1537189A

Description

TECHNICAL FIELD

The present invention relates to a rope usable for an elevator and mechanical handling equipment.
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.
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.
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.
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 10 µm and less than 20 µm, 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.
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.
US 4 197 695 A discloses a rope with the features in the pre-characterizing portion of claim 1. US 4 550 559 A discloses another related cable formed by coated strand constitutes.

DISCLOSURE OF THE INVENTION

In the above proposed 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.
According to the present invention, these conventional drawbacks are overcome to obtain a soft and long-life rope with preferable frictional coefficient.
The rope of the invention is defined in Claim 1. Further advantageous features of the invention are set out in the dependent claims.
Here, "join" means an adhesion by an adhesive, a fusion bonding between two members by heating, a bonding by chemical treatment and so forth.
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

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 constitute forming the rope of Fig. 2.
Fig. 4 is a cross sectional view showing another embodiment of the coated constitute forming the rope of Fig. 2.
Fig. 5 is a cross sectional view showing an embodiment of a coated constitute forming the rope of Fig. 2.
Fig. 6 is a cross sectional view showing an embodiment of a coated constitute 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. the coated constitute 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

Fig. 1 is an overall view showing an embodiment of an elevator to which a rope of the invention is applied.
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.
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.
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.
Figs. 2 and 9 are cross sectional views showing a rope 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.
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.
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.
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.
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.
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.
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.
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 fifteenth 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.
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.
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.
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.
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.
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.
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 six 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.
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.
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.
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.
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.
Fig. 12 shows another embodiment of a rope. This is basically similar to the embodiment of Fig. 7, but the core coated constitute 12 is formed by twisting the wires 31 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.
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.
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.
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.
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.
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.
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.
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.
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

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.

Claims

A rope (10) for an elevator comprising
a first coated constitute (12; 20, 30) in which a first constitute (22, 32) of twisted metallic wires (21, 31) is coated with and adhered to a first coating member (23, 33),
second coated constitutes (13; 20, 30) in each of which a second constitute (22, 32) of twisted metallic wires (21, 31) is coated with and adhered to a second coating member (23, 33), the second coated constitutes (13; 20, 30) surrounding the first coated constitute (12; 20, 30) with a clearance between adjacent second coated constitutes (13; 20, 30),
a third coating member (11) with which an outer periphery of the second coated constitutes (13; 20, 30) is coated, the third coating member (11) extending in the clearance to be joined to the first and second coating members (23, 33),
wherein the first and second coating members (23, 33) are made of an elastic organic material;
characterized in that
the first and second constitutes (22, 32) have a strand structure in which the metallic wires (21) are twisted, adjacent ones of the twisted metallic wires (21) being in line contact with each other, or a structure in which strands (34, 35) are twisted, each of the strands (34, 35) being formed by twisting the metallic wires (31), adjacent ones of the twisted metallic wires (31) in each strand (34, 35) being in line contact with each other; and
the diameter of each of the metallic wires (21, 31) of the first and second constitutes (22, 32) is between one hundredth and one fifteenth of the diameter of the outer periphery of the rope (10) without the third coating member (11).
The rope (10) according to claim 1, wherein the second coating members (23, 33) are formed of an inner coating material capable of being joined with the second constitutes (22, 32), and the third coating member (11) is formed of an outer coating material capable of having an appropriate frictional coefficient with respect to a sheave.
The rope (10) according to claim 1, wherein thicknesses of the first and second coating members (23, 33) are 0.2-0.5 mm.
The rope (10) according to claim 1, wherein the second and third coating members (23, 33; 11) are joined by fusion bonding, adhesive or chemical bonding.
The rope (10) according to claim 1, wherein the second coating member (23, 33) and the metallic wires (21, 31) of the second constitutes (22, 32) are bonded by adhesive or chemical bonding.