Wire stripper having rotary driving means

An apparatus for removing insulation from an insulated, flat multiconductor cable comprises a body having a channel therein for lateral receipt of the cable. The apparatus includes blades for slicing the cable insulation during insertion into the channel. A rotary driving mechanism is provided for drawing the cable through the channel away from the cutter to thereby remove the sliced insulation. The apparatus includes means associated with the driving mechanism to enable lateral cable insertion into the driving mechanism in non-interfering relation while simultaneously inserting the cable into the cutter.

FIELD OF THE INVENTION 
This invention relates to an apparatus for removing insulation from an 
insulated cable, in particular, a flat multiconductor cable having a 
plurality of individually insulated conductors. 
BACKGROUND OF THE INVENTION 
In the telephone, communications and data transmission industries, 
increasing use is being made of flat multiconductor cable of the type 
including a planar array of individually insulated conductors surrounded 
by a sheath or jacket of insulative material. In addition, there is more 
use, for example, in the telephone industry of modular plug type 
connectors. Such modular connectors are mounted on floor terminals which 
in turn are desirably electrically connected by the flat multiconductor 
cable to a wall terminal block, the flat cable extending unobtrusively 
beneath floor carpeting. 
Because of the modern office requirements for office layout flexibility, 
field installation of telephone terminals and associated cable connections 
is necessary. In connecting an end of the cable to ancillary electrical 
terminals, couplings or the like, the cable end is to be stripped of its 
outer insulative sheath with the insulation of the individual conductors 
remaining intact. In field applications, where sophisticated wire 
stripping devices are often not readily available and are relatively 
costly, resort has been had to a variety of manual stripping tools. These 
conventional stripping devices have a tendency in pulling off the outer 
sheath to also pull off some or all of the insulation of the individual 
conductors. Accordingly, it is desirable to remove the outer insulative 
shield without damaging the individual conductor insulation with a device 
that has particular use in field installations. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an improved apparatus 
for removing insulation from an insulated cable, such apparatus being 
particularly suited for removing insulation from an insulated flat, 
multiconductor cable. 
In accordance with the invention, insulation removing apparatus comprises a 
housing supporting cutting means wherein the cutting means includes 
insulation cutting surfaces defining an opening for receipt therein of an 
insulated cable along a predetermined direction. The housing further 
supports rotary drive means in spaced disposition relative to the cutting 
means. The rotary drive means is adapted to engage a portion of the 
insulated cable and pull such cable portion away from the cutting means 
during rotation of the driving means. The apparatus includes means 
providing for substantially non-interfering insertion of the cable into 
the rotary drive means along a direction common to the direction of cable 
insertion into the opening of the cutting surfaces. 
According to a preferred form of the invention, the housing is a body 
having an elongate, open channel for receipt laterally therein of a flat 
multiconductor cable. The channel has two opposed wall surfaces spaced 
apart a distance to be closely adjacent the outer flat cable insulation 
surfaces. In this preferred arrangement, means are provided for 
establishing at the rotary drive means an access opening of measure not 
less than the approximate spacing of the channel wall surfaces, whereby 
the cable may be inserted laterally into the channel in interfering 
relation with the cutting means and in substantially non-interfering 
relation with the rotary drive means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawing, there is shown in FIG. 1 a conventional flat 
multiconductor cable 10 of the type that the stripping device of the 
present invention is particularly suited to accommodate, the cable 10 
being shown in its treated condition. The cable 10 comprises a plurality 
of elongate conductors 12 extending in a substantially planar array, each 
conductor 12 being individually surrounded by a suitable layer of 
insulation 14. The insulated conductors 12 are fully surrounded by an 
outer sheath or jacket 16 of insulation, the jacketed cable 10 having two 
opposing substantially flat insulation surfaces 16a and 16b, 
respectively. The sheath 16 may be of the type comprising amounts of 
carbon or other suitably conductive elements to thereby provide a cable 
useful in telephone or other communications applications. It should be 
understood that the cable 10 is described herein for illustrative purposes 
and that cables of other construction may have insulation removed 
therefrom in accordance with the principles of the invention as described 
hereinbelow. 
Turning now to FIGS. 2, 3 and 4, an insulation stripping device 18 is 
shown, the stripping device 18 in its preferred arrangement being of the 
manually operable type and of size to be held in the palm of an operator's 
hand. The device 18 comprises a body 20 that houses a cable insulation 
cutter 22 and a rotary driving mechanism 24. The body 20 is an elongate 
block-type member, generally rectangular in cross-section and is formed of 
a suitably rigid material, which may be a plastic or metal. Other body 
configurations and shapes may also be used. An elongate channel 26 is 
formed to extend within the body 20 throughout its length and preferably 
extends into the body 20 a portion of its depth. The channel 26 is formed 
to have an opening 26a that extends through an outer wall 20a of the body 
20 and to have two opposing, substantially parallel, wall surfaces 28 and 
30. The channel width, i.e., the spacing between the wall surfaces 28 and 
30, is formed to be slightly greater than the thickness of the flat cable 
10, i.e., across its two flat surfaces 16a and 16b. Accordingly, with a 
close clearance between the channel walls and the cable, the channel 26 
upon receiving the cable therein serves as a cable guide to maintain the 
cable in a suitable position for stripping as will be detailed. The 
channel 26 and thereby the cable guide is provided to precede and succeed 
the insulation cutter 22 as at 26b and 26c, respectively, channel portion 
26c extending between the cutter 22 and the rotary driving mechanism 24. 
Referring now to FIGS. 4, 5, 6 and 7, the details of the insulation cutter 
may be more fully understood. The cutter 22 preferably comprises a pair of 
spaced blade members 32 and 34, formed preferably of a hardened steel or 
other suitable material. The blade members are suitably mounted into the 
body 20 as, for example, by press fitting, and in communication with the 
channel 26. The blade members each have cutting surfaces 32a and 34a and 
stepped-down surfaces 32b and 34b, respectively. The opposing cutting 
surfaces 32a and 34a are relatively sharp, as indicated in FIG. 6, and are 
disposed in the body 20 to present an opening 36 in interference relation 
to the cable 10 when received in the channel 26. The spacing S.sub.1 
between the cutting surfaces 32a and 34a is arranged to be less than the 
thickness of the cable 10 but greater than the outer diameter of the 
insulation 14 on the individual conductors. Accordingly, when the cable 10 
is laterally inserted into the channel, the sharp cutting surfaces 32a and 
34a will slice the outer sheath 16, but will not cut the conductor 
insulation 14. 
The stepped-down surfaces 32b and 34b are flattened slightly to provide 
relatively blunt surfaces as shown in FIG. 7. The spacing S.sub.2 between 
the opposing blunt surfaces 32b and 34b accordingly is greater than the 
spacing S.sub.1 and in the preferred form spacing S.sub.2 is less than the 
thickness of the cable 10. Also in the preferred arrangement, the spacing 
S.sub.2 is provided between the blade members 32 and 34 along a length 
S.sub.3 that is greater than the width or lateral extent of the cable 10. 
The blunt edges 32b and 34b are provided as a means for preventing 
inadvertent nicking of the cable 10 as it is drawn through the channel 
during the stripping operation as will be described. It should be 
appreciated that while the blade members have been described herein as a 
pair of separate members a single integral cutter with a suitable slot or 
the like may also be used in the practice of the invention. 
Referring again to FIGS. 2 and 3, the details of the rotary driving 
mechanism 24 are illustrated. The rotary driving mechanism 24 comprises a 
generally cylindrical driving wheel 38 having a flat portion 38a extending 
axially along the wheel 38 and defining a geometric chord intersecting the 
wheel circumference. Around the circumference of the wheel 38, except at 
the flat portion 38a there are a plurality of radially projecting teeth 40 
which extend axially along the wheel 38, the teeth 40 preferably formed in 
ratchet-like configuration. The wheel 38 is supported by the body at a 
fixed location spaced longitudinally from the cutter 22 and is adapted to 
communicate with the channel 26 and to rotate about an axis 42, such axis 
42 being offset relative to the channel 26. The axis 42 is offset at a 
predetermined distance from and extends transversely to the channel 26 
such that upon rotation of the driving wheel 38 the teeth 40 are 
periodically moved into the channel 26 at a position between the channel 
wall surfaces 28 and 30. Such movement into the channel enables the teeth 
to engage a cable within the channel and, in cooperation with channel wall 
surface 28, to draw such cable therethrough. Also, upon rotation of the 
driving wheel 38, the flat portion 38a is periodically aligned 
substantially coplanarly with the channel wall surface 30, this position 
being as shown in FIG. 3. In this position, the flat portion 38a 
establishes at the driving mechanism 24 a cable access opening 26d of 
measure approximately the same as the channel spacing, i.e., the distance 
between wall surfaces 28 and 30. It should be appreciated that the driving 
wheel 38 offset or the flat portion 38a may be formed to provide an 
opening 26d that is greater than the channel spacing but not less than the 
approximate channel spacing so that cable may be inserted into the channel 
26 at the rotary driving mechanism in substantially non-interfering 
relation. 
The driving wheel 38 is manually rotatable in accordance with the preferred 
embodiment by a knob 44 suitably fixedly coupled to the driving wheel 38 
by a shaft 46. The driving wheel 38 may be arranged to be movably retained 
in the position shown in FIG. 3 so as to facilitate cable loading by a 
suitable detent. Such detent may be in the form of a spring loaded, ball 
detent set screw 48 threadably supported by the body 20 and adapted to 
periodically engage a flat portion on the shaft 46. 
Having described the details of the insulation stripping device 10, the 
operation thereof may now be understood with reference to the drawing 
figures, particularly FIG. 8. The device 10 is initially manipulated such 
that the flat portion 38a of the driving wheel 38 coincides coplanarly 
with the channel wall 30. A cable, such as the cable of FIG. 1 but 
unprepared, is inserted laterally into the channel 26 whereby during such 
insertion one portion of the cable is engaged by the insulation cutter 22 
while another portion of the cable is simultaneously moved into the rotary 
driving mechanism in non-interfering relation. Continued insertion causes 
the cutting surfaces 32a and 34a to slice the cable insulation across the 
cable width along cable insulation surfaces 16a and 16b, respectively. 
Further lateral insertion moves the cable past the cutting surfaces 32a 
and 34a and into engagement with the blunt edges 32b and 34b. As the 
spacing S.sub.2 between the blunt edges 32b and 34b is less than the cable 
thickness, the cable insulation cannot pass through the cutter 22 in a 
rightward direction in FIG. 8. The knob 44 and thereby the driving wheel 
38 are turned in a counter-clockwise rotation as indicated in FIG. 8 
thereby moving the driving wheel out of the detent and causing the teeth 
40 to engage and grasp the cable 10 within the channel 26. Continued 
rotation of the knob 44 causes longitudinal movement of the cable 10, 
whereby the cable 10 inclusive of the insulated conductors 12 is drawn 
within the channel and the insulation remnant 16 is restrained from 
movement by the cutter 22 and is thereby stripped from the cable as the 
cable is drawn longitudinally away from the cutter 22. The cable guides 
provided by the channel portions 26b and 26c, both fore and aft of the 
cutter, serve to maintain the cable substantially centralized and stable 
during cable movement thereby minimizing damage to the conductor 
insulation during stripping. The rotary driving wheel provides a leveraged 
advance of the cable during the drawing operation whereby substantially 
uniform force is applied to the cable across its width. 
Having described the insulation stripping device of the present invention 
herein, it should be appreciated that other variations thereof may be 
employed during the practice thereof. For example, while simplicity and 
cost advantages attend the rotary driving wheel with a flattened portion, 
the driving mechanism may be provided with one or more rotatable members 
for drawing the cable wherein movement may be imparted through spring 
biasing or the like to such wheels so as to allow clearance for lateral 
cable insertion. Also, while the insulation stripping device has been 
described herein as manually operable, it should be appreciated that the 
device may be modified to function automatically within the contemplation 
of the invention. 
The particularly disclosed and depicted embodiments of the invention and 
methods are thus intended in an illustrative and not in a limiting sense. 
The true spirit and scope of the invention are set forth in the following 
claims.