Stock material or miscellaneous articles – All metal or with adjacent metals – Having variation in thickness
Reexamination Certificate
1999-02-19
2001-11-20
Zimmerman, John J. (Department: 1775)
Stock material or miscellaneous articles
All metal or with adjacent metals
Having variation in thickness
C428S457000, C428S687000, C254S13430R
Reexamination Certificate
active
06319618
ABSTRACT:
BACKGROUND AND FIELD OF THE INVENTION
The present invention is directed to an article known in the electrical and allied trades as a “fish tape”, which is an elongate, flexible tape, or messenger, intended to draw electrical wires, optical cables and the like through tubular conduits emplaced in the walls of buildings. The fish tape, which may be supplied in lengths of up to 200 feet, is advanced through conduits, i.e., from a first junction box to a second remote junction box. The fish tape includes at its rear end portion a holding means for securing wire or cable to be emplaced, i.e., a hook swivel or the like, and at its front end portion, some type of blunt or rounded end. After the wire or cable is secured to the holding means at the rear free end of the tape, the tape is withdrawn carrying with it the wire whereby the wire is disposed in the desired connecting relation between the junction boxes.
PRIOR ART
Conventional fish tapes have been made of a variety of materials. These materials must meet a wide range of service characteristics including high tensile strength, high flexibility enabling the lead end to travel, and the body of the tape to bend, about obstructions and resistance to buckling when a pushing force is exerted on a tape.
The material heretofore regularly employed for the fabrication of fish tape has been carbon steel wire. A major difficulty with such conventional materials is the lack of sufficient corrosion resistance; rust greatly increases the frictional resistance to advancing the tape through the conduits, and in addition runs the risk of contaminating wires or cables already emplaced; a further complication is that the persons handling the wire are dirtied as well. Further, carbon steel fish tapes often leave detritus on the walls or carpeting where used in new installations or installations within existing buildings. Earlier attempts to avoid the corrosion problem utilized so-called “blue finish”, or hardened and tempered steel tapes. However, such ‘blue’ tapes were more costly than regular steel tapes, and did not full resolve the problem: even the ‘blue’ tapes tended to rust, apparently as a result of their treatment were even more likely to be brittle, and less elastic, and susceptible to failure under stress.
A further concern in limiting the opportunities for alternative materials for tape fabrication, is the need to form the holding means at one end, utilizing the same material of the tape. The holding means usually is formed by bending a free end of the tape to form what is referred to as the “pulling loop”. The fabrication of a pulling loop with a conventional carbon steel tape is readily accomplished by heating and cooling prior to bending the form hook. These operations must be carefully conducted in order not to compromise the tensile strength or durability of the critical hook end.
The difficulty of running wires and data transmission cables such as fiber optic cables by conventional tape means has lead to many ideas to reduce the friction problem of the fish tape. By way of example, U.S. Pat. No. 1,597,706(?)proposed coating internal surface of the conduits with a wax coating to reduce feed friction. However, the use of a wax in addition to creating a fire hazard, can be counter-productive under certain circumstances, in that friction can actually be increased where dust and dirt become embedded in the wax.
It has also been proposed to reduce stress during the pulling of cable through conduit, especially when installing fiber optic data transmission cables, which are far more fragile than conventional wires, by injecting a liquid into the duct line, thereby reducing the friction encountered during feed. The problem with this proposed solution resides in the fact that the lubricating fluid must be removed after cable emplacement and the conduit completely and carefully dried. (see EP 4445622 and EP 665993). This is clearly a time consuming and costly procedure.
In EP 620627, it is proposed to utilize compressed air as a conveying medium for communication cables within conduits. This method is said to reduce the buildup of a static charge in the conduit. However, the method is noisy and results in driving dust through various junction boxes.
Attempts to minimize frictional resistance to pulling the tapes through conduits include cladding tapes with coatings such as nylon; such coatings have enjoyed only limited success since the coatings are readily stripped from the tape where the cable bends around obstacles, thus quickly losing its effect and leaving a residue within the conduit.
SUMMARY OF THE INVENTION
The present invention is directed to an improved fish tape fabricated of stainless steel. More particularly, the invention is directed to a stainless steel fish tape characterized by the composition of the steel, within certain parameters. The desirable steel provides the necessary tensile and compressive strength for the desired thickness and width of the tape, for the desirable bendabililty required for the formation of the pulling loop, the required flexibility to enable the tape to pass beyond and around obstacles in the conduit, and a freedom from corrosion which will ensure low friction feed and a long useful life. The more flexible stainless steel tape also is more easily wound up for easy storage and use.
A further significant advantage of the fish tape of the present invention resides in its versatility, i.e., the ability to prepare the external surfaces of the tape in either a smooth condition, or when additional lubricant, or the like, is needed for the surface treatment of the tape, the surface may be abraded or roughened to provide channels for retaining small amounts of lubricant on the tape surfaces. Not only is the feed of the tape itself facilitated, but also small amounts of the lubricant will be rubbed off from the tape, at the conduit bends, which will coat the precise areas within the conduit where the wires to be pulled through are most likely to rub. In other words, by being capable of providing a roughened external surface, without fear of excessive corrosion, and which can be coated with lubricant, the feed of the tape is facilitated as is the return feed of the wires through the conduit.
In accordance with a further embodiment of the invention, the major surfaces of the tape are provided with one or more longitudinally extending channels. These channels not only provide an additional repository for portions of lubricant, but in addition improve the flexibility of the tape.
It is important in understanding the advance of the instant invention to recognize that the versatility of having the optional capability of being provided with an abraded or roughened surface on the tape, in those circumstances where a surface coating is desirable, is exactly contrary to the requirements for the fish tapes heretofore known. It has been considered necessary to provide surfaces which are as smooth and bright as possible, in order to reduce sites for increased corrosion.
It is accordingly an object of the invention to provide a stainless steel fish tape. A further object of the invention is the provision a fish tape capable of having and maintaining a bright smooth finish, a high degree of flexibility as well as a high tensile strength, throughout its length. It is further an object to provide a fish tape material which can be readily formed into a pull hook at one end without loss of tensile strength or flexible at that crucial location.
A still further object of the invention is the provision of a stainless steel tape which can be given roughened outer surfaces, adapted to receive and retain increments of a lubricant, without significant corrosion occurring. By providing lubricant in this manner, relatively small quantities can be provided to result in the desired decrease in friction without creating sticky surfaces which might collect dirt or other contaminants. The lubricant functions during feed of the tape as a friction reducing medium. The lubricant in addition providing a low friction return path for the ta
Ampolini Axel V.
Groening Manfred
Kelley George R.
Smoljan Arthur J.
Magidoff Barry G.
Zapp USA, Inc.
Zimmerman John J.
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