Wire cutter structure for multipurpose tool

A multipurpose tool may have several tool elements which pivot into storage positions in profiled handles attached to one of a pair of pliers jaws. A wire-cutter portion of each pliers jaw includes a sharp edge and a notch located at the throat of the pair of jaws, adjacent the sharp edge. The notches face toward each other to support and shear wire, but the bottoms of the notches are prevented from passing each other so that bulging material at the bottoms of the notches does not cause the jaws to bind against each other.

BACKGROUND OF THE INVENTION 
This invention relates to a wire cutter arrangement for a hand tool and 
more particularly to wire cutter portions of pliers jaws of a compact 
multipurpose tool. 
Compact multipurpose hand tools, of which the types shown in Leatherman 
U.S. Pat. No. 4,888,869, Frazer U.S. Pat. No. 5,267,366, and Sessions et 
al. U.S. Pat. No. 5,142,721 are examples, include pliers, handles, and 
other tool elements arranged in such a way that the size of the tool is 
reduced when it is not in use. The pliers in such tools, to provide added 
functions for the user, preferably include wire cutters, and for ease of 
manufacture, the wire cutters preferably have blades with sharp edges 
which pass by each other in scissors fashion. 
These wire cutters work well and 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 edges of the wire 
cutter blades, the wire cutter edges may be deformed, causing the blades 
of the wire cutter to bind against each other and tending to hold the 
pliers including such blades in a closed position. This can render the 
tool very difficult to use. 
Additionally, the straight edges of such scissors-action wire cutters often 
tend to squeeze wire away from the fulcrum of the jaws before beginning to 
cut it, thus reducing the mechanical advantage available through the 
pliers handles. 
Haeberli U.S. Pat. No. 871,585 discloses pliers which include a wire 
cutting notch in the throat of a pair of scissors-action shearing blades, 
but the wire cutting notches have their openings extending generally 
radially outward, away from the pivot axis of the pliers, and the wire 
cutting notches move entirely past one another, so that in using such 
pliers to cut wire approaching the hardness of the material of the tool 
itself, it is likely that deformation of the material defining the notches 
"j" would result in added friction between the jaws of the pliers. 
Klever, Jr. U.S. Pat. No. 667,914 discloses a multipurpose scissors tool 
whose handles include a pair of wire cutter notches "g" whose open mouths 
are directed radially away from the pivot axis of movement of the handles 
with respect to each other. As in the Haeberli tool, deformation of the 
material defining the wire cutter notches is likely to cause the tool 
parts to bind against each other. 
What is needed in a hand tool, then, is an improved scissors-action wire 
cutter intended to cut hard wire, yet which is less susceptible than those 
of previously known wire cutters to having one wire cutter portion become 
bound against its mate; and in particular such an improved wire cutter is 
desired for a compact multipurpose tool. 
SUMMARY OF THE INVENTION 
The present invention overcomes the aforementioned shortcomings and 
disadvantages of prior art wire cutters and provides a wire cutter portion 
for a tool having a pair of jaws pivoted for movement with respect to each 
other in pliers fashion, in which a pair of notches defined by the jaws 
hold a wire and shear it apart, but are deep enough so that they continue 
to define an opening between their opposed interior surfaces when the jaws 
are in a fully closed position. 
In one embodiment of the invention the notches are defined in a pair of 
wire cutter blades, adjacent sharp edges which interact with each other in 
scissors fashion, with the notches being located near the jaw pivot axis 
about which the wire cutter blades move with respect to each other. 
In one embodiment of the invention the wire cutter is included in a pliers 
portion of a compact multipurpose tool. 
It is an important advantage of the wire cutter of the present invention 
that it can cut hard wires without thereby causing its blades to bind 
against each other and be difficult to open. 
The foregoing and other objectives, features, and advantages of the 
invention will be more readily understood upon consideration of the 
following detailed description of the invention, taken in conjunction with 
the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIGS. 1, 2 and 3 show a compact multipurpose tool 14 including the improved 
wire cutter blade configuration of the present invention. It should be 
noted that, although FIGS. 1, 2, and 3, and subsequent description 
thereof, do describe one type of compact multipurpose tool, application of 
the preferred embodiment is not limited to tools of that particular 
configuration. Moreover, the present invention is intended to encompass 
all types of multipurpose tools, wire cutting pliers, wire cutters, and 
metal shears which incorporate a scissors-type cutting action. The tool 14 
includes a pair of pliers jaws 16, connected to each other pivotally by a 
conventional jaw pivot joint defining a pivot axis 18. Each jaw 16 has an 
associated handle member 20. Each handle member 20 of the tool 14 houses 
several tool elements 22 which pivot independently of one another about a 
respective pin 24 located at an outer end of each of the handle members 
20. The handle members 20 are constructed of profiled sheet metal, each 
having a pair of parallel sidewalls 26 interconnected by the base 28, 
which serves as the back of the handle member 20. The pins 24 are mounted 
in and extend between the sidewalls 26 to attach the respective tool 
blades 22 to each handle member 20. 
Each handle member 20 is connected to a respective one of the jaws 16 by a 
jaw handle pin defining a pivot axis 30. The tool elements 22 are located 
in respective storage positions within the profiled handle members 20, as 
shown in FIG. 2. The tool 14, when closed, is relatively small and has a 
convenient exterior shape to be carried in a pocket of one's clothing. 
As shown in FIG. 3, when the jaws 16 are extended with respect to the 
handle members 20 and the tool blades 22 are all stored within the 
profiled handle members 20, the multipurpose tool 14 is conveniently 
useful as a pair of pliers including wire cutters. 
As shown in FIGS. 4, 5, 6 and 7, prior art compact multipurpose tools 
similar in many respects to the tool 14 also include pliers jaws 16', 
which include wire cutter portions. Each jaw 16' includes a wire cutter 
portion 34 having a sharp edge 36 defined along the intersection of a flat 
inner face 38 with a flat outer face 40. The inner faces 38 of a pair of 
such jaws 16' are substantially coplanar, so that pivoting the jaws 16' 
toward each other results in scissors-like interaction of the wire cutter 
portions 34, with their sharp edges 36 sliding past each other toward an 
overlapping relationship and defining a cutting plane. Each sharp edge 36 
is forced into the surface of a wire being cut, acting as a knife at the 
same time the wire cutter portions 34 are also placing opposing shearing 
forces on the wire being cut. When cutting wires whose hardness approaches 
that of the sharp edge 36, not only is the wire deformed and ultimately 
cut, but the metal of the wire cutter portion 34 is likely to be upset as 
well, as shown at 42. Not only does the upset portion 42 result in a 
reduced sharpness of the edge 36 at that location, but some of the upset 
material 44 is displaced laterally, in the direction of the inner face 38 
of the other wire cutter portion 34. As shown in FIG. 7, the laterally 
displaced material 44 associated with each sharp edge 36 thereafter rubs 
against the inner face 38 of the opposing wire cutter portion 34, 
increasing the amount of friction which must be overcome in moving the 
jaws 16' relative to each other in either direction. 
While the additional force required to overcome such friction can often be 
provided by the user when opening and closing the jaws, the additional 
friction is often objectionable to the user and also causes the tips of 
the jaws to be laterally offset from each other, reducing the precision of 
the needlenose pliers jaws 16' of the tool. 
The wire cutter of the present invention, as shown in FIGS. 8-13, includes 
a pair of jaws 16 including wire cutter blades 50 each including a sharp 
edge 52 formed along the intersection between an inner face 54 and an 
outer face 56. The inner faces 54 are substantially parallel and coplanar, 
so that they slide past each other in scissors fashion in the same manner 
as in the prior art wire cutter portions 34 shown in FIG. 6, defining a 
cutting plane 58. 
At the radially inner end of each wire cutter blade 50, that is, at the end 
of the sharp edge 52 closer to the jaw pivot axis 18, is a crescent-shaped 
notch 60 defined by each wire cutter blade 50. The notches 60 are thus 
located immediately adjacent a hub portion 61 that surrounds the jaw pivot 
axis 18 of each jaw 16, as may be seen best in FIGS. 9 and 10. While the 
notches 60 shown in the drawings of the present application are shown as 
having open mouths facing toward each other, and as being in the shape of 
circular arcs, other shapes could also be used. 
As shown best in FIGS. 11 and 12, the notches 60 are defined by generally 
cylindrical surfaces 62, including bottom surfaces 63, extending 
transversely with respect to the jaws 16, substantially normal to the 
respective inner face 54. The cylindrical surfaces 62, then, and 
especially the bottom surfaces 63, rather than acting as knife edges to 
cut into the surface of a wire (such as the wire 64 shown in FIG. 10 and 
shown in phantom view in FIG. 11), provide support against the surfaces of 
the wire 64 over a significant area. Thus, the cylindrical surfaces 62 of 
the two notches 60 act on opposite sides of a wire such as the wire 64 to 
shear it apart along the cutting plane 58. 
Referring particularly to FIGS. 8, 9 and 13, it will be seen that the 
bottom surfaces 63 of the notches 60 do not pass entirely by each other 
when the jaws 16 of the pliers portion of the tool 14 are moved to the 
fully closed position, with gripping faces 17 in contact with each other. 
Instead, a small amount of clearance is left between the opposed bottom 
surfaces 63 so that the notches 60 define an opening 66 through the 
cutting plane 58. 
In a preferred embodiment of the invention, the pliers jaws 16 are shaped 
by conventional methods so that the inner face 54 and outer face 56 define 
the sharp edge 52, and the notch 60 is provided in each jaw 16. The sharp 
edge 52 of the wire cutting blade 50 may include an angle 68 of between 
45.degree. and 75.degree., and includes an angle 68 of about 60.degree., 
for example, in one embodiment of the invention, between the inner face 54 
and the outer face 56. The inner face 54 in such an embodiment of the 
invention has a height 70 of 1.52 mm (0.060 inch), while the 
crescent-shaped notch 60 has a depth 72 of 0.51 mm (0.020 inch), so that 
when the jaws 16 are in the fully closed position shown in FIG. 8, the 
opening 66 has a height 74 (FIG. 13) of 0.038 mm (0.0015 inch) before the 
wire cutter is used to cut very hard wire. 
The height 74 of the opening 66 is thus small enough initially that wires 
of as small a diameter as are likely to be encountered in normal use are 
sheared sufficiently to fail by the time the jaws 16 are in the fully 
closed position shown in FIG. 13. Mechanical failure of the wire takes 
place primarily through shearing action, as parts of the wire 64 on 
opposite sides of the cutting plane 58 are moved in opposite directions 
along the cutting plane 58, supported by the cylindrical surfaces 62 
defining the notches 60. The sloping lower faces 78 of the jaw 16 may also 
exert a force to push the wire 64 away from the cutting plane as indicated 
by the arrow in FIG. 13, depending on the size of the wire 64. 
The notches 60, by extending around a portion of a wire, prevent the wire 
from sliding outwardly along the wire cutter blades 50 in a radial 
direction away from the jaw pivot axis 18. As a result, cutting of hard 
wires such as the wire 64 takes place as close as possible to the jaw 
pivot axis 18, making use of the maximum mechanical advantage available 
through the handle members 20. 
Because the bottom surfaces 63 of the notches 60 do not pass each other on 
the cutting plane 58, as the jaws 16 rotate with respect to each other 
about the pivot axis 18, any deformation of the material surrounding the 
notches 60, as shown at 80 in FIG. 13, bulges into the opening 66 when the 
jaws 16 are in their fully closed position also shown in FIGS. 8 and 9. As 
a result, even though the bottom surfaces 63 defining the notches 60 may 
be deformed slightly as a result of the forces imposed by the action of 
cutting a wire 64 whose hardness approaches that of the material of the 
jaws 16, the resulting deformity will not cause the jaws 16 to interfere 
with one another and resist opening the wire cutter jaws after such a hard 
wire 64 has been cut. 
The invention additionally avoids having such jaw interference offset the 
precise alignment of the needlenose tips of the jaws 16. As a result, the 
pliers jaws 16 of a compact tool 14 such as that shown in FIGS. 1-3 can 
easily be opened without worry that the handle members 20 will rotate 
inappropriately with respect to the jaws 16, about the jaw handle pin 
pivot axes 30, after the wire cutter blades 50 have been used to cut hard 
wires. 
At the same time, moreover, the sharp edges 52 of the wire cutter blades 50 
remain available for scissors-action cutting of soft wires or very small 
diameter wires, or for use on a limited basis to cut sheet material. 
Finally, the notches 60 add an improved wire stripping capability to the 
compact multipurpose tool 14. 
The terms and expressions which have been employed in the foregoing 
specification are used therein as terms of description and not of 
limitations, and there is no intention, in the use of such terms and 
expressions, of excluding equivalents of the features shown and described 
or portions thereof, it being recognized that the scope of the invention 
is defined and limited only by the claims which follow.