Tools – Wire stripper – Pivoted blade
Reexamination Certificate
2001-09-28
2002-07-16
Smith, James G. (Department: 3723)
Tools
Wire stripper
Pivoted blade
C081S009400, C030S091200
Reexamination Certificate
active
06418817
ABSTRACT:
BACKGROUND INFORMATION
1. Field of the Invention
The invention relates to V-notch wire strippers and particularly, to wire strippers with an adjustable stop mechanism for adjusting the wire stripper to a specific wire gauge.
2. Description of the Prior Art
Wire strippers have long been known and there are numerous variations on the basic device. The critical feature of the wire stripper is to provide the capability of adjusting a stop for the cutters so that, when the device is closed, the cutters cut through the insulation around the wire, but do not nick or damage the wire conductor. The conventional wire stripper today has two cutter bars that are movably attached to each other in an intermediate section of the bars such that when the handgrips at one end of the cutter bars are closed, the cutter jaws at the other end of the bars close around the wire to be stripped. Typically, each cutter jaw has a V-notch in the cutting area so that when the cutting jaws close toward each other, a cross-section that corresponds to the cross-section of the uninsulated wire conductor remains open and the cutting edges of the cutting jaws cut through only the insulation. The goal of all such strippers is to establish the minimum opening between the cutter jaws that will snugly embrace the stripped wire, i.e. the minimum opening that will cut through the insulation without damaging the wire itself, when the handgrips are squeezed together.
Since it is critical that the strippers don't close too closely around the wire, wire strippers typically have some type of adjusting mechanism or stop mechanism to set the minimum opening of the cutter jaws. The types of stop or adjusting mechanisms include cams, star-shaped wheels, and nut-and-screw slides in a groove. These mechanisms are mounted on a lower portion of one of the cutter bars and effectively stop the other cutter bar from closing too far. Many of these mechanisms require the use of a screwdriver or other tool to adjust the mechanism. This is a disadvantage, because it generally takes two hands to hold the wire stripper around a wire to adjust the stripper to the proper gauge. To have to use a screwdriver or other tool to loosen or tighten the adjusting mechanism is cumbersome and leads to inaccuracy. A shortcoming of the conventional adjusting or stop mechanisms, however, is that they do not provide for a safety clearance to ensure that the cutter jaws do not nick the conductor. Thus, determining the proper adjustment for the tool still requires guesswork on the part of the person using the tool and possibly several trials and corrections of the tool.
A further disadvantage of many of the conventional devices is that the adjusting mechanism “walks” when it is being set. For example, one can adjust the stripper to properly fit the wire gauge, only to have the mechanism move slightly during tightening, with the end result that the cutter jaws close too closely and then cut into the wire when the stripper grippers are squeezed closed, or are too far apart so that the jaws do not cut through the insulation properly, making it difficult to strip it from the conductor. In addition, most wire strippers have a spring mechanism that biases the cutters and grippers to an open position. The spring bias is generally desirable, because it ensures that the stripper will spring open when one's grip on the grippers is released. The disadvantage of this spring bias, however, is that it increases the difficulty of accurately adjusting the stripper, because the hand gripping the wire stripper has to counteract the biasing force of the spring during adjustment. Because of these disadvantages of conventional wire strippers, adjusting the wire stripper is typically a trial-and-error operation that requires very careful visual inspection and may require several trial cuts before the tool is properly adjusted.
What is needed, therefore, is a wire stripper with an adjustable stop mechanism that will allow the operator of the tool to quickly and easily change or adjust the setting of the stripper, with excellent accuracy and repeatability. What is further needed is such a device that will automatically provide clearance for the uninsulated conductor, without the need to use additional tools or to know the wire gauge. What is yet further needed is such a device that provides a means of controlling a biasing spring to achieve the desired bias function and to quickly and easily convert the bias function of the spring to a hold function that holds the current position of the stripper.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a V-notch wire stripper that has an accurate and easily adjustable stop mechanism for setting the minimum proximity of the cutter jaws. The term “minimum proximity” or also “minimum opening” refers to the size of the opening in the cutter jaws that fits snugly around the bare wire when the stripper is closed. It is a further object of the invention to provide such a wire stripper that does not require the use of an additional tool such as a screwdriver to adjust the minimum proximity of the cutter jaws. It is a yet further object to provide such a wire stripper that automatically provides a safety clearance for the uninsulated wire. It is a still yet further object to provide such a stripper that has a biasing spring that, in a first position, biases the cutter bars open, but can be easily placed into a second position that helps to hold the then current opening of the stripper.
The objects are achieved by providing a wire stripper that has an adjustable stop mechanism that includes a cam and a slider mounted in a groove on one of the cutter bars. The slider has a tab on its upper end and another tab on its lower end. These tabs fit within the groove and serve as guides, allowing the slider to move along a section of the cutter bar. A detent, in some embodiments a hemispherical protrusion, is provided on the upper face of the slider. The cam also has a lever along one side which can be used to move the cam into a HOLD position, a CUT position, or into a RELEASE position. When the cam lever is pushed to the RELEASE position, the slider can be moved along the groove; when pushed to the HOLD position, the detente applies sufficient force against the slider to hold the slider in position in the groove; and when pushed to the CUT position, the position of the cam is adapted such to force the cutter bars apart slightly, so that the cutter bars cut through the insulation on the wire, yet provide a security clearance between the cutter edges and the conductor.
To adjust the stripper for a particular wire gauge, the operator first checks that the cam is in the RELEASE position. The operator then places a piece of uninsulated wire into the V-notch area of the cutter jaws and brings the cutter jaws together around the wire, such that the jaws close snugly around the wire, but without cutting into it. If uninsulated wire is not available, the operator can, of course, place a piece of insulated wire in the stripper and gently squeeze the grippers until he or she senses that the cutter jaws have cut through the insulation and just touched the wire. Once the cutter jaws have been brought into light contact with bare wire, the operator then slides the slider in the groove with the other hand until the edge of the slider touches the edge of the other cutter bar. At this point, the operator pushes the cam lever all the way to an inner stop that forces the cutter bars to open slightly more, thereby automatically providing the correct clearance for allowing the cutters to cut through the insulation without marking or damaging the conductor.
REFERENCES:
patent: 2868049 (1959-01-01), Radcliffe
patent: 2968096 (1961-01-01), Bonito et al.
patent: 2997787 (1961-08-01), Wheeler
patent: 3130616 (1964-04-01), Miller
patent: 3172133 (1965-03-01), Rizzo
patent: 3283404 (1966-11-01), Hickman
patent: 3733627 (1973-05-01), Epstein
patent: 3854202 (1974-12-01), Cortese et al.
patent: 3872746 (1975-03-01), Wittes et al.
patent: 389085
Bohan Thomas L.
Mathers Patricia M.
Shakeri Hadi
Smith James G.
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