Spring devices – Fibrous
Reexamination Certificate
2000-03-29
2001-09-18
Butler, Douglas C. (Department: 3613)
Spring devices
Fibrous
C029S896930, C267S136000, C267S166000, C188S378000, C248S570000
Reexamination Certificate
active
06290217
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to vibrational energy isolators, and in particular, wire rope isolators. More specifically, but without restriction to the particular embodiment hereinafter described in accordance with the best mode of practice, this invention relates to wire rope vibration isolators employing a minimum of one asymmetric mounting block retaining a disconnected wire rope shaped into an asymmetric loop design.
2. Background of the Prior Art
Excessive vibrational energy can damage and/or cause the deterioration of sophisticated machinery. In industries in which movement is inherent in daily operations, such as avionics and shipping, the need to minimize unwanted vibrational energy is imperative. These industries have come to rely heavily on sensitive electronic equipment, like navigational computers, to maintain daily operations. Constant jostling of electronic equipment can cause system failures that lead to costly downtime to replace and/or repair the damaged equipment.
Over the years, many devices have been designed to isolate damaging vibrations and isolate unwanted kinetic energy. These devices use the unwanted kinetic energy to move simple machinery, like pistons and springs, so as to divert the energy from shock-sensitive equipment attached to the isolator. A good example of a member of this class of devices is the wire rope isolator. The most common wire rope isolators employ a helical wire cable secured between a pair of retaining members. When the isolator is in use, vibrational energy causes the wire rope coil to move in a spring-like fashion, which in turn moves the retaining members vertically toward each other. This movement diminishes the degree of vibrational energy transferred to the affixed sensitive equipment.
The art of wire rope vibration isolators has been contributed to by a number of proposed devices detailed in U.S. Pat. No. 5,549,285 issued to Collins and U.S. Pat. Nos. 5,441,243 and 5,791,636 both issued to Loziuk. These patents describe vibrational energy energy isolators that consist of coiled wire ropes secured between two parallel retaining blocks. Holes drilled into the retaining blocks maintain the helical shape of the wire rope. Vibrational energy causes the wire rope coil to contract which in turn moves the entrapment blocks vertically relative to each other thus absorbing vibrational energy in the process.
There are disadvantages with the helical design. Conventional helical wire rope isolators are ineffective when the support load is a few pounds. In addition, helical wire rope isolators are not well suited for applications with spatial restrictions or significant weight limitations due to the need that the wire coil be of a certain length to be functional. It was therefore desirable to design a wire rope isolator that overcame the limitations associated with traditional helical wire rope isolators. U.S. patent application Ser. No. 09/496,688, incorporated herein by reference, discloses a wire rope vibration isolator that includes a pair of mounting blocks spaced apart by wire rope manipulated into four U-shaped bights. The bights form a cloverleaf-type pattern between the two blocks. To maintain the bight formation, the mounting blocks are crimped into locking contact with the wire rope. When exposed to vibrational energy, the wire rope bights flex causing the mounting blocks to move toward each other expending the unwanted energy in the process.
The wire rope isolator disclosed in U.S. application Ser. No. 09/496,688 successfully solves the problems associated with traditional helical wire rope isolators. The disclosed isolator is capable of supporting relatively light loads. Due to the simpler design, relatively small-scale wire rope isolators can be constructed for applications having limited space. Manufacturing costs are decreased due to ability to use cheaper materials.
It was discovered, however, that applying a tension force to the wire rope during the crimping process reduced dimensional and stiffness variation in the isolator. The design disclosed in the '688 application employs a continuous loop of wire rope having both ends located in the same hole thus prohibiting the use of a tensile force during the crimping process. It was found that locating both ends of the wire rope in the same retaining hole unnecessarily complicated the manufacturing of the isolator, thus increasing production costs. Accordingly, it is highly desirable to design a wire rope vibrational energy isolator with all of the attributes of the design disclosed in U.S. patent application Ser. No. 09/496,688 while maintaining tensile force in the wire rope during manufacture so that dimensional and stiffness qualities are uniform throughout the isolator.
SUMMARY OF THE INVENTION
It is, therefore, a general object of the present invention to provide a new and. improved wire rope isolator.
It is an object of the present invention to simplify the design of wire rope isolators.
A further object of the present invention is to produce a relatively small-scale isolator for use in applications with spatial limitations.
Still another object of the present invention is to construct a wire rope isolator suited to support relatively light masses.
It is yet a further object of the present invention to manufacture wire rope isolators using cost-effective materials.
An additional objective of the present invention is to develop a method of manufacturing a wire rope isolator using a singular tool and a limited number of fastening means.
Yet a further object of the present invention is to design a wire rope isolator without a closed loop design thus reducing manufacturing error and complexity.
Still yet another objective of the present invention is to be able to maintain tension in the wire rope throughout the crimping process to minimize dimensional and stiffness variation.
These and other objects are attained in accordance with the present invention of a wire rope vibration isolator that includes a pair of mounting blocks spaced apart by a singular wire rope or a number of wire ropes manipulated into a cloverleaf pattern about the blocks. According to one aspect of the present invention, a first mounting block contains, at one end, a pair of closely spaced lateral holes. In the preferred embodiment, one of the pair is a blind hole used to position the end of the wire rope during assembly. The other hole of the pair passes axially therethrough the mounting block. Another through hole is located on the opposite end of the same mounting block. In other embodiments, both holes of the closely spaced pair are either blind or through holes and a pair of holes, instead of one, may be situated at the opposite end of the mounting block.
A second mounting block contains, at opposing ends of the block, two through holes, although in other embodiments of the present invention the second mounting block is although in other embodiments of the present invention the second mounting block is identical to the previously described first mounting block. One end of the wire rope is positioned in the blind hole of the asymmetrical block. The free end of wire rope is arched outward forming a U-shaped bight and then passed completely through the opposing hole of the second mounting block. The wire rope is arched outward again forming a second U-shaped bight between the two mounting blocks. The wire rope is then passed completely through the lone hole of the asymmetric mounting block. The wire rope is again arched outward forming a third U-shaped bight and is passed completely through the empty hole of the second mounting block. A fourth U-shaped bight is formed as the wire rope is arched outward from the second mounting block into the empty hole of the first mounting block. The wire rope is pulled completely therethrough. The tension in the rope is maintained while a crimp is formed at each lateral hole to secure the wire rope in place.
REFERENCES:
patent: 3044759 (1962-07-01), Kerley, Jr.
patent: 3360225 (1967-12-01), Camossi
Dickerson Kenneth A.
Latvis Michael
Schneider Stefan
Butler Douglas C.
Enidine Incorporated
Wall Marjama & Bilinski
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