Patent Application
20110114908
Elevator systems carry passengers, cargo or both between different levels in a building, for example. Some elevator systems operate on a hydraulic machine arrangement to move the elevator car as desired. Other elevator systems are traction-based and rely upon traction between a traction sheave and an elevator roping arrangement to cause desired movement of the elevator car.
Typical traction-based elevator systems include a roping arrangement that has a plurality of tension members such as steel ropes or flat belts, for example. The roping arrangement follows a path defined by sheaves placed strategically within the elevator system. At least one of the sheaves operates as a traction sheave causing the roping arrangement to move responsive to operation of a machine that causes the traction sheave to rotate. Other sheaves are considered idler sheaves that move responsive to movement of the roping arrangement. Controlling the direction and speed of movement of the traction sheave provides the ability to move the elevator car in a desired direction at a desired speed.
It is necessary to have sufficient traction between the traction sheave and the tension members to achieve desired elevator car movement and to control car position, for example. Where round steel rope tension members are used, specially shaped grooves or plastic liners within grooves are used for traction purposes. In systems using flat belts as the tension members, the conventional approach to having a sufficient traction surface on a traction sheave involves sandblasting a steel surface to roughen it. A roughened surface provides more traction than a smoother surface, for example.
It is also necessary to avoid corrosion of an elevator sheave. In round rope systems, lubricant is applied to the ropes. The lubricant provides some corrosion protection. The conventional approach to avoid corrosion in belted systems has been to plate the roughened surface of the sheave with a corrosion resistant material such as hard chrome. The plating protects the surface of the sheave from wear and corrosion.
One shortcoming of the conventional approach is that plating over the roughened surface of the sheave tends to change surface characteristics such as reducing the roughness. This is especially true if the plating has any appreciable thickness. Typically, plating is kept to a maximum thickness of two microns to minimize altering the desired roughness of the sheave surface. One drawback associated with such a thin plating layer is that it is likely to crack or have voids. Leaving the metal of the sheave surface exposed along such cracks or voids leaves the surface susceptible to corrosion, for example. Additionally, any wear of the very thin layer leaves exposed metal.
There are other uses of metal components that require a corrosion and wear resistant coating outside of elevator systems.
It would be desirable to provide better wear and corrosion protection while still being able to achieve the necessary surface characteristics for a given situation.
An exemplary method of making a first component for contacting another component includes applying a wear and corrosion resistant material layer onto a surface of the first component. The corrosion resistant material layer is then roughened subsequent to having been applied to the surface.
An exemplary component includes a metallic body having a surface that is adapted to contact another component. A corrosion resistant material layer on the surface has a thickness that is greater than about 5 microns.
The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
For discussion purposes an elevator system and an elevator component that requires wear and corrosion protection are used as an example implementation.
A traction sheave 30 and an idler sheave 32 establish a path along which the roping arrangement 26 travels for purposes of moving the elevator car 22 as desired. An elevator machine 34 causes the necessary movement of the traction sheave 30 to achieve the desired elevator car movement. In certain exemplary applications, the traction sheave 30 could be a surface of the machine shaft rather than a separate component.
The traction sheave 30 has a roughened surface to achieve the necessary traction between the tension members of the roping arrangement 26 and an appropriate surface on the traction sheave 30. The traction sheave 30 also has a corrosion resistant material on the surfaces that are adapted to contact the tension members of the roping arrangement 26.
One example corrosion resistant material comprises electroless nickel. Another example comprises electroless nickel and between 5% and 10% phosphorous. Electronic nickel is another example material. Other example corrosion resistant materials include hard chromes such as a hard nodular chrome or a trivalent metallic chrome. Such materials are selected for their hardness, wear resistance and corrosion resistance properties.
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Prior to this invention it was believed that blasting after applying a corrosion resistant material would cause cracking. Therefore, the conventional technique involved applying a very thin layer (e.g., two microns thick) of a corrosion resistant material onto a previously roughened surface. Such a thin layer was required to maintain the desired roughness of the surface. Such a thin layer, however, prevented any subsequent treatment because it would result in cracking the plating on the surface. The example technique differs substantially from previous techniques in that the corrosion resistant material layer is roughened after it is applied to the surface.
With the disclosed example technique, it is possible to apply a thicker layer of corrosion resistant material. A thicker layer provides longer-lasting wear and corrosion resistance and allows for subsequently treating that layer to achieve the desired roughness. One example includes a thickness of at least 5 microns for the corrosion resistant material layer 42. Another example includes a thickness up to 60 microns. One particular example has a thickness between 15 and 30 microns. Such thicknesses are useful for providing corrosion protection, wear resistance and the ability to roughen the surface of the layer 42 without causing it to crack or otherwise be damaged in an undesirable manner. Depending on the selected thickness of the corrosion resistant material layer 42 and the particular blasting media, the particulars of the blasting technique can be tuned to achieve a desired roughness while avoiding cracking the applied material layer 42. Given this description, those skilled in the art will be able to achieve a desired roughness for their particular application that meets their particular needs.
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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.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US08/69129 | 7/3/2008 | WO | 00 | 12/10/2010 |
