Compact multi-purpose hand tools contain pliers, screwdrivers, knife blades, saws, can and bottle openers, and other tool elements arranged and connected to a handle structure in such a way that the size of the tool is reduced when the tool is not in use. Examples of such tools are shown in U.S. Pat. Nos. 4,888,869 to Leatherman, 5,142,721 to Sessions et al., 5,267,366 to Frazer, and 6,009,582 to Harrison et al. The pliers in such tools, to provide added functions for the user, preferably include wire cutters, and for case of manufacture, the wire cutters are preferably formed on a pair of plier jaws and have sharp edges that pass by each other in scissors fashion.
The wire cutters disclosed in the patents referenced above cleanly cut wires whose hardness is significantly less than the hardness of the wire cutters. However, when used to cut wires whose hardness approaches that of the sharp wire cutter edges, the edges may be deformed by the hard wire (e.g., burred). Such deformation of the wire cutter edges may cause the inner surfaces of the wire cutters to bind against each other and either lock the plier jaws in a closed position and/or prevent the plier jaws from opening and closing properly. This is especially alarming for compact, multipurpose tools for two reasons. First, since the plier jaws included with such tools are pivotally connected to and fold within channels formed in the handle structures, any additional force required to separate plier jaws binded by deformations may cause unintended folding and partial closure of the handles with respect to the jaws without necessarily opening the binded jaws. Second, if the plier jaws are successfully separated, a user may have difficulty returning the tool to its most compact configuration because the deformations will prevent the plier jaws from closing completely.
U.S. Pat. No. 5,826,338 to Chilton et al. discloses a multipurpose tool with plier jaws having wire cutter blades 50 with notches 60. Chilton seeks to alleviate the problems caused by deformations on the wire cutter blades 50 by disclosing notches 60 with bottom surfaces 63 that do not pass entirely by each other when the plier jaws are in the fully closed position. Thus, Chilton's notches are formed so that a clearance space 66 is left between opposed bottom surfaces 63 of notches 60 when the plier jaws are completely closed (see FIGS. 9 and 10 of the Chilton patent). Thus, even if small burrs are formed on or adjacent the bottom surfaces of the notches, the notches do not need to clear each other and the burrs, therefore, do not adversely impact opening or closing of the plier jaws.
As mentioned above, however, Chilton's notches do not completely pass one another when the plier jaws are fully closed. Thus, the Chilton device will not properly cut some small diameter wires because the bottom surfaces of the notches will not make sufficient contact with these wires.
If no clearance space is left between the bottom surfaces of the notches, then the flat bottom surfaces are nonetheless desirable because they are less likely to be deformed by hard wires than are sharp cutting edges. However, such flat bottom surfaces still deform upon cutting hard wire, and cause binding of the plier jaws if no clearance is left between those surfaces.
It is therefore desirable to provide a notched wire cutting structure capable of cutting wires of all sizes, while minimizing or negating the effects of deformations caused by hard-wire cutting.
USPTO Backgrounds
USPTO Backgrounds