ELEVATOR LOAD BEARING MEMBER INCLUDING A UNIDIRECTIONAL WEAVE

Abstract

A method of making an elevator load bearing member includes unidirectional weaving a plurality of load bearing fibers including at least a first material and a second material. A melting point of the first material is higher than a melting point of the second material. The method includes bonding the load bearing fibers together by at least partially melting at least some of the second material and coating the plurality of load bearing fibers.

Claims

1. A method of making an elevator load bearing member, the method comprising: unidirectional weaving a plurality of load bearing fibers including at least a first material and a second material, wherein a melting point of the first material is higher than a melting point of the second material; bonding the load bearing fibers together by at least partially melting at least some of the second material; and coating the plurality of load bearing fibers.

2. The method of claim 1, wherein the first material comprises a first type of polymer; the second material comprises a second type of polymer; at least some of the load bearing fibers comprise the first type of polymer; and at least some others of the load bearing fibers comprise the second type of polymer.

3. The method of claim 1, wherein at least some of the load bearing fibers comprise the first material and the second material.

4. The method of claim 1, wherein the coating comprises applying a jacket onto the load bearing fibers; and the jacket defines a traction surface of the elevator load bearing member.

5. The method of claim 4, wherein the jacket comprises a thermoplastic material; and the coating comprises applying an adhesive onto the load bearing fibers between the thermoplastic material and at least some of the load bearing fibers.

6. The method of claim 1, wherein the bonding comprises heating and applying pressure to the load bearing fibers.

7. The method of claim 6, wherein the heating includes exposing the load bearing fibers to a temperature that is at least as high as the melting point of the second material and below the melting point of the first material.

8. The method of claim 6, wherein the bonding comprises pressing the load bearing fibers between first rollers that are heated; and pressing the load bearing fibers between second rollers that are not heated.

9. The method of claim 1, wherein a ratio of the first material to the second material is between 1:1 and 4:1.

10. The method of claim 9, wherein the ratio is 2:1.

11. The method of claim 1, wherein the first material comprises at least one of carbon, liquid crystal polymer, aramid, polyhydroquinone-diimidazopyridine, polybenzimidazole, polypyridobisimidazole and polybenzoxazole; and the second material comprises at least one of ultrahigh molecular weight polyethylene and ultrahigh molecular weight polypropylene.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 schematically illustrates selected portions of an elevator system including a load bearing member designed according to an embodiment of this invention.

[0026] FIG. 2 schematically illustrates an example embodiment of an elevator load bearing member.

[0027] FIG. 3 is an end view of another example embodiment of an elevator load bearing member.

[0028] FIG. 4 schematically illustrates selected features of a process for making an elevator load bearing member like those shown in FIGS. 2 and 3.

DETAILED DESCRIPTION

[0029] FIG. 1 schematically shows selected portions of an elevator system 20 including an elevator car 22 and counterweight 24. A traction sheave 26 associated with a machine (not specifically illustrated) selectively controls movement of a load bearing member 30, which suspends the elevator car 22 and counterweight 24, to control the movement or position of the elevator car 22. For illustration purposes, a single load bearing member 30 is represented in FIG. 1. Multiple load bearing members would be included in many embodiments.

[0030] FIG. 2 schematically illustrates an example load bearing member 30. A plurality of load bearing fibers 32 serve as the primary load bearing components of the load bearing member 30. The load bearing fibers 32 are woven into a unidirectional weave. The load bearing fibers 32 are arranged as warp fibers extending in a length direction L of the load bearing member 30. A unidirectional weave has fibers extending in a single direction and does not include weft fibers that would be parallel to a width direction W of the load bearing member.

[0031] In some embodiments the unidirectional weave may include some weft fibers transverse to the single direction of the warp fibers but such weft fibers are far fewer in number than the warp fibers and are not considered significant to the load bearing performance of the unidirectional weave. Any such weft fibers may serve a limited purpose during manufacturing, for example.

[0032] Weaving the load bearing fibers into a unidirectional weave avoids any braiding of the fibers and, therefore, provides improved strength characteristics compared to other types of weaves. A unidirectional weave of load bearing fibers 32 also provides improved flexibility characteristics.

[0033] In the embodiment shown in FIG. 2, the load bearing fibers 32 are arranged or grouped as cords 34 and the cords 34 are woven into the unidirectional weave. In the embodiment shown in FIG. 3, the load bearing fibers 32 are individually woven into the unidirectional weave, which effectively forms a layer or sheet 36.

[0034] .

[0035] The load bearing fibers 32 include at least two different types of material. Some embodiments include at least one polymer and another type of material such as carbon or another organic material. One of the materials is selected to at least partially melt for bonding the load bearing fibers 32 together. The material that provides the bonding has properties including a melting point that allows for at least partially melting that material without compromising the mechanical properties of another material that at least some of the other load bearing fibers 32 are made.

[0036] For discussion purposes, the illustrated example embodiment includes a first type of polymer material and a second type of polymer material that have different melting points. The first type of polymer material has a higher melting point than the melting point of the second type of polymer material. Including different types of polymer with different melting points allows for bonding the load bearing fibers 32 of the unidirectional weave together in a way that preserves the mechanical properties of the fibers made of the first type of polymer and maintains the configuration of the unidirectional weave. For example, the plurality of load bearing fibers 32 are bonded together by at least some of the second type of polymer that is at least partially melted without melting any of the first type of polymer material.

[0037] In some embodiments each of the load bearing fibers 32 comprises only one type of polymer. For example, some of the fibers 32 are made of the first type of polymer while others are made of the second type of polymer. In other embodiments at least some of the fibers 32 include more than one material and may include multiple polymers or at least one type of polymer and another type of material.

[0038] The unidirectional weave of fibers 32 includes a ratio of the first type of polymer to the second type of polymer (e.g., higher melting point polymer to lower melting point polymer) in a range from 4:1 to 1:1. Some embodiments include a ratio of the first type of polymer to the second type of polymer of 3:2. An example embodiment includes a ratio of 2:1. In preparation of the multi-polymer composite, the ratio of high melt point fibers to low melting point fibers depends on the processing and linear density of the fibers.

[0039] The unidirectional woven fibers are consolidated under a selected pressure at the specific temperature that the second or low melting point polymer material melts and forms a hot fluid that adheres the higher melting point fibers together. On cooling from the consolidated high temperature, the low melting point polymer fibers recrystallize, which forms a resin matrix in composite. The original mechanical properties of the low melting point polymer fibers will change because they are at least partially melted. Including the higher melting point material allows for preserving the mechanical properties of the higher melting point fibers. The final property of the composite provides the necessary characteristics for elevator system operation when there are enough higher melting point fibers, such as having more higher melting point fibers than lower melting point polymer fibers.

[0040] Example higher melting point and high strength polymers include liquid crystal polymer, aramid, polyhydroquinone-diimidazopyridine, polybenzimidazole, polypyridobisimidazole and polybenzoxazole. Example lower melting point and high strength polymers include ultrahigh molecular weight polyethylene and ultrahigh molecular weight polypropylene.

[0041] A jacket 38 covers the load bearing fibers in each of the illustrated example embodiments. The jacket 38 comprises a material that is suitable for establishing the desired traction with the traction sheave 26 to achieve the desired traction for controlling movement of the elevator car 22. Example materials that are useful include compressible materials, such as a thermoplastic material or an elastomer. In some embodiments the jacket 36 comprises a thermoplastic polyurethane material.

[0042] FIG. 4 schematically illustrates an example method of making the disclosed load bearing member embodiments. The plurality of polymer load bearing fibers 32 are introduced or fed into unidirectional weaving equipment 40 where the fibers 32 are woven into the unidirectional weave. Then the woven fibers 32 are heated and pressed together by bonding equipment 42. For example, the bonding equipment 42 includes heating elements that subject the woven fibers 32 to a temperature that is at least as high as the melting point of the second type of polymer and less than the melting point of the first type of polymer. Such heating at least partially melts at least some of the second type of polymer without melting any of the first type of polymer. Any fibers composed of only the first type of polymer are not melted or altered during such heating.

[0043] In the illustrated example arrangement the unidirectionally woven fibers 32 are fed through and pressed between heated rollers 44. At least the rollers 44 heat the woven fibers 32 to a temperature sufficient to at least partially melt at least some of the second type of polymer. That melted polymer bonds the woven fibers 32 together.

[0044] In FIG. 4, the bonding equipment 42 includes cooling rollers 46 to facilitate shaping or maintaining the shape of the unidirectional weave of fibers 32 while any melted polymer recrystallizes.

[0045] Once the unidirectional weave is at a suitable temperature it is coated by coating equipment 50. In the illustrated example arrangement, the coating equipment 50 includes an adhesive applicator 52 that applies an adhesive coating onto the polymer load bearing fibers 32. A jacket application device 54, such as an extruder, applies the material of the jacket 38.

[0046] A load bearing member including a multi-polymer unidirectional weave of load bearing fibers as disclosed above provides improved strength characteristics compared to traditional elevator roping or belts that rely on steel wires as the primary load bearing components. Additionally, load bearing members consistent with the example embodiments of this disclosure are lighter weight and provide cost savings compared to previous configurations.

[0047] The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.