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Publication numberUS3906561 A
Publication typeGrant
Publication dateSep 23, 1975
Filing dateApr 22, 1974
Priority dateApr 22, 1974
Also published asCA1022747A, CA1022747A1
Publication numberUS 3906561 A, US 3906561A, US-A-3906561, US3906561 A, US3906561A
InventorsBawa Jaspal S
Original AssigneeThomas & Betts Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pliers-type hand tool with attached insulation slitting blade
US 3906561 A
Abstract
An extendable stripper blade attached to a jaw of a cutting tool is provided with means for biasing the blade in a retracted position while the sharpened end of the blade is encompassed within a protective cover preventing inadvertent contact with the blade during handling and use. The biasing means may comprise a spring member cooperative with support means on both the blade and the cover, the latter having a housing portion overlying the spring. The blade means may be further provided with a stop member releasably engaging the spring housing in a first or lock position, and manipulable to a release position to permit the retracted blade to be extended for use.
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Description  (OCR text may contain errors)

United States Patent [1 1 Bawa [ Sept. 23, 1975 PLIERS-TYPE HAND TOOL WITH ATTACHED INSULATION SLITTING [21] App1.No.: 472,108

[52] US. Cl. 7/5.4; 30/90.4; 30/162; 30/317 [51] Int. Cl. B25B 7/22 [58] Field of Search 30/90.4, 90.6, 90.7, 91.2, 30/162, 317, 320, 294, 335; 7/3 R, 5.4, 5.1

[56] References Cited UNITED STATES PATENTS 52,645 2/1866 Kellogg 7/5.l X

114,820 5/1871 Holmes et a1 7/5.4

135.734 2/1873 Southwick 7/5.4

164,575 6/1875 McCall 30/162 463,912 11/1891 McVitty 30/906 X 851,482 4/1907 Barnett 30/320 X 1,201,872 10/1916 Richel 30/162 X 1,866,095 7/1932 Foley ISO/90.7

2,370.733 3/1945 Jones 30/907 2501.409 4/1952 Dahl 30/162 x 3,520,057 7/1970 Gore a a1 .0 30/102 FOREIGN PATENTS OR APPLICATIONS 56,650 7/1891 Germany .j 30/907 Primary ExaminerAl Lawrence Smith Assistant Examiner-J. T. Zatarga Attorney, Agent, or Firm-David Teschner; Jesse Woldman [57] ABSTRACT An extendable stripper blade attached to a jaw of a cutting tool is provided with means for biasing the blade in a retracted position while the sharpened end of the blade is encompassed within a protective cover 7 12 Claims, 10 Drawing Figures S-Patent Se t.23,1975 She etl'of 2 3,906,561

US Pamnt Sept 23,1975 Sheet 2 of2 3,996,51

z? 26 56 M M "AVA/NM MAM PLIERS-TYPE HAND TOOL WITH ATTACHED INSULATION SLITTING BLADE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is directed to the field of protective devices for cutting tools and the like.

2. Description of the Prior Art Cutting tools, according to the prior art, may be provided with stripping or slitting blades adapted to be fastened to one of the tool jaws to longitudinally slit aselective length of insulation surrounding an insulated conductor, which insulation has been circumferentially severed by the cutting blades of the tool to provide a bared length of conductor adaptable for'connection to a further member. :In a particular embodiment, the blade is permitted to slide freely along the jaw of the tool and is extended and retracted by manual manipulation so that upon completion of the slitting operation the extended sharpened end of the blade must be man tively shield the sharpened blade end during rapid manipulation of the tool, and are therefore of only limited reliability and effectiveness in use. With the increasing emphasis upon tool safety there is an increasing need for'reliable, simple, inexpensive, automatic, and effective protective devices for cutting tools and thelike to insure operator safety during use and handling.

SUMMARY OF THE INVENTION The invention overcomes the limitations and difficulties noted above with respect to prior art devices by providing a rapid, safe, reliable, automatic, and effec tive protective device for cutting tools and the likev Disposed over an extendable blade having a sharpened end for stripping the insulation from an insulated conductor or the like is a cover means attached to a jaw member of the tool upon whichthe blade means is movably mounted. A portion of the cover means overlies the sharpened end of the blade means so that, in the retracted position, the sharpened blade end is disposed between an adjacent portion of the respective tool jaw and the overlying portion of the cover means, the sharpened blade end thus being protectively shielded from inadvertent contactby the user. The covermeans may further include a housing portion in which is disposed biasing means such as a spring memberfor biasing the blade means in the retracted positionso that the;

user must overcome the biasing spring to manipulate the blade to the extended position to expose the sharpened end thereof. Upon removal of the force required to maintain the blade in its extended position, the blade is caused to be automatically rapidly returned to its re-' tracted position within the protective enclosure of the cover means. Thus, in a typicalapplication, the blade is forcibly manipulated to its extended position and the hooked end thereof brought intoengagementwith the insulation of an insulated conductor so that the blade is maintained in its extended position while the hooked end of the blade is guided through the slitting operation. Upon completion of the slit and the consequent release of the force counteracting the biasing means, the sharpened blade end is caused to retract rapidly to a position within the confines of the cover portion which reestablishes the protective guard thereover. Fastening means such as a threaded screw having an unthreaded shank portion engagable with a slotted portion in the blade means may be employed to guide the blade along a fixed path of travel from the retracted to the extended position. The cover means may also-be provided with a folded lip portion adjacent either one orboth lateral edges thereof to more fully enclose the sharpened blade end and, where necessary or desirable, to provide additional guide means therefore. To facilitate manipulation of the blade means, the end thereof remote from the sharpened end may be provided with a finger support which may comprise an upstanding portion extending outwardly from the body of the blade means and suitably located to permit convenient access thereto by, for example, the thumb of the user. A further protrusion may be provided which extends upwardly from-the blade body for normal engagement with the housing portion of the cover means to provide a stop means arranged to prevent extension of the blade until disengaged by the user, thus entailing a twostep procedure for unlocking the blade means and extending it into its operative position. It is therefore an object of this invention to provide an improved tool.

It is another object of this invention to provide means for protecting the sharpened blade end of a stripper blade. j t

It is a further object of this invention to provide an improved tool having an attached extendable stripper blade biasedto a retracted position within the confines of the tool jaws.

It is yet another object of this invention to provide cover means for a sharpened blade attached to the jaw of atoolto provide a protective enclosure therefore.

It. is still another object of this invention to provide means for insuring automatic retraction of a sharpened tool blade to a position within the confines ofa protective cover upon removal of the extending force thereto.

.lt is yet a further object of this invention to provide means for biasing an extendable blade in a retracted position'during periods of non-use.

It is still a further object of this invention to provide an improved tool having biased blade means releasably locked in a retracted position.

Other objects and features of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode contemplated for carrying'it out.

BRIEFDESCRIPTION OF THE DRAWINGS I In the Drawings FIG. 1 is a fragmentary top plan view, partly cut away and partly in section, showing an improved tool constructed-in accordance with the concepts of the invention.

FIG. 2 is an exploded perspective view showing various elements of the device illustrated in FIG. 1.

FIG. 3 is a fragmentary side elevational view, partly in section, showing the elements illustrated in FIG. 2 in an' assembled condition.

FIG. 4 is a top plan view, partly cut away and partly in section, of the device of FIG. 1 with the blade means thereof in its extended position.

FIG. 5 is a top plan view, partly cut away and partly in section, of the device of FIG. 1 showing its use thereof to provide a slit through the insulation of an insulated conductor.

FIG. 6 is a fragmentary perspective view of a further embodiment of a cover means of an improved tool constructed in accordance with the concepts of the invention.

FIG. 7 is a top view, partly cut away and partly in sec tion, of a further embodiment of biasing means for the blade member of an improved tool constructed in accordance with the concepts of the invention.

FIG. 8 is a fragmentary front elevational view, in section, taken along the line 88 of FIG. 7.

FIG. 9 is a fragmentary front elevational view, in section, showing a further embodiment of a portion of an improved tool constructed in accordance with the concepts of the invention.

FIG. 10 is a fragmentary front elevational view, in section, of the device illustrated in FIG. 9, showing the manner in which the blade means is released from look ing engagement with the cover means.

Similar elements are given similar reference characters in each of the respective drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

Turning now to FIGS. 1, 2, 3 and 4 there is shown in dotted outline a first jaw means and a second jaw means 22 of an improved tool 24 constructed in accordance with the concepts of the invention. Attached to the second jaw means 22 is a cover means 26 provided with a selectively shaped forward portion 28 overlying a sharpened first end 30 of a blade means 32 biased into a retracted position by a spring 34 situated within a housing portion 36 of the cover means 26. The cover means 26 is attached to the second jaw member 22 by a fastening means, such as a screw 38, having an unthreaded shank portion 40 adapted to slidably fit within a slotted portion 42 extending longitudinally within the blade means 32. The threaded end 44 of the fastener 38 is adapted to engage a threaded hole 46 (FIG. 3) in the second jaw member 22. To facilitate manual manipulation of the blade means 32 against the force of the biasing spring 34 the second end 48 of the blade means 32 is provided with an upstanding leg portion 50 serving as a finger support, as shown more clearly in FIG. 4. Thus, by applying pressure in the direction indicated by the arrow 52 in FIG. 4, the blade means 32 may be urged into its extended position so that the sharpened blade end 30 is exposed beyond the front portion 28 of the cover means 26. The housing portion 36 of the cover means 26 is suitably formed in a boxlike arrangement to provide an enclosure for the spring 34 in the manner shown in FIG. 3. The spring 34 is confined between a first end 54 of the housing portion 36 and an upstanding protrusion 56 shown as lanced out of the body portion of the blade means 32 at a distance selectively spaced from the second end 48 of the blade means. Thus, the elements 54 and 56 provide support for the biasing spring 34 so that upon movement of the blade means 32 in the direction illustrated by the arrow 52 in FIG. 4, the spring 34 is compressed between the supporting elements 54 and 56. Consequently, upon release of the blade means 32, the spring 34 will tend to turn to its free state thereby rapidly and automatically urging the blade means 32 back into the retracted position substantially as shown in FIG. 1. As further illustrated in FIG. 2, the front portion 28 of the cover means 26 may be provided with a turned down lip 58 serving to further encompass the retracted front end 30 of the blade means 32. Although the lip portion 58 bordering one edge of the cover means front portion 28 will generally provide adequate protection for the sharpened blade end 30 there may be provided a second lip portion 60 bordering the opposing edge of the front portion 28, as illustrated in FIG. 6, to encompass both sides of sharpened blade end 30, where necessary or desirable. The lip portions 58 and 60 may of course be selectively spaced so as to receive the blade means 32 relatively closely therebetween to provide, for example, a channel-like guide therefor. It will of course be evident to those skilled in the art that both lip portions 58 and 60 may be eliminated from the cover means 26 since the blade means 32 will be adequately guided by the shank portion 40 of the fastening means 38. The upstanding lanced portion 56 may be lengthed as illustrated, for example, at 62 in FIG. 9 so as to pro vide a free end 64 arranged to abut the opposing end 66 of the cover means housing portion 36 when the blade means 32 is in its retracted position. Accordingly, extension of the blade means 32 requires initially manipulating the blade means in a direction transverse to the longitudinal axis of the blade means as illustrated by the arrow 68, sufficiently to cause the lanced portion end 64 to clear the opposing end 66 of the housing portion 36, as illustrated in greater detail in FIG. 10, and thereafter applying a longitudinally directed force, as shown, for example, in FIG. 4, so that the free end 64 of the upstanding lanced portion 62 rides along the adjacent inner surface of the housing portion 36, whereby the blade means may be moved forward or to the left as viewed in FIG. 10. Although not illustrated, the housing portion 36 may be suitably slotted or grooved forward of its end 66 to provide clearance for the free end 64 of the upstanding lanced portion 62 so that after said end 64 has been disengaged from the housing portion end 66 it may ride freely within the slot or groove as the blade means is manipulated to its extended position.

Turning now to FIG. 5 the sharpened blade end 30 is shown extended beyond the front portion 28 of the cover means 26 and in engagement with an insulated covering 70 disposed about an insulated conductor 72. The blade end 30 is maintained in the extended position during the slitting operation by the force exerted thereon by the yet unslit portion of the insulating covering 70, the underside of which is engaged by the hooked portion 74 of the sharpened blade end 30 so that as the tool 24 is pulled along the right, as viewed in FIG. 5 during the slitting operation, the blade means 32 is held in the extended position while the sharpened blade end 30 negotiates the length of the insulation 70 desired to be stripped from the conductor 72 while the finger pressure initially employed to extend the blade means has been heretofore removed. As the hooked portion 74 of the blade end 30 reaches the end of the insulation 70 the extending force is no longer available to maintain the blade means 32 in the extended position at which point the biasing spring 34 operates to retract the extended blade end 30 back under the front portion 28 of the cover means 26 to the position shown in FIG. 1. Consequently, the blade end 30 is now fully protected from inadvertent contact by the user.

Referring now to FIGS. 7 and 8 there is shown a further embodiment of a cover means 78 and associated blade means 80 constructed in accordance with the concepts of the invention. In this arrangement, the biasing means comprises an extension spring 82 having a first end 84 attached to a support 86 mounted on the blade means 80 and a second end 88 attached to a sup port 90 attached to the inner surface of the cover means 78 at the end thereof remote from a front end 92 overlying a sharpened blade end 94 of the blade means 80. To insure biasing the blade means 80 in a retracted position, the spring 82 is extended slightly between the supports 86 and 90. Thus, upon manipulation of the blade means towards the left, as viewed in FIG. 8, to extend the sharpened blade end 94 beyond the front portion 92 of the cover means 78, the spring 82 is further extended thereby exerting a retracting force on the blade means 80 tending to counteract the extending force applied thereto. The spring 82 is enclosed within sides 96 and 98 of the cover means 78, which sides may also be advantageously employed to provide a guide means for the blade means 80 along its path of travel between its retracted and extended positions. The cover means 78 may be provided with flanged portions I00 and 102 for fastening the cover means to an associated tool jaw (not shown). Each of the flanged portions 100 and 102 is provided with an aperture 104 and 106, respectively through which may be inserted a fastener such as a screw, rivet, or the like, for securing the cover means 78 to its associated tool jaw.

The embodiments of the invention in which an exclusive property or privelege is claimed are defined as follows:

I. In a pliers-type hand tool having a first jaw means and a second jaw means pivotally coupled to one another, handle means extending rearwardly from each of said first and second jaw means for moving said jaw means, and blade means coupled to a selective one of said first and secondjaw means and having a sharpened first end movable from a first position located within the periphery of said selective one of said first and said second jaw means to a second position located beyond the periphery of said selective one of said first and said second jaw means for engagement with the insulation of an insulated conductor, the improvement comprising: said blade means being located on an exterior surface of said selective one of said first and said second jaw means. said blade means first end being slidably extendable along an axis generally coincident with the longitudinal axis of said tool and forwardly of the bight formed by the closure of said first and said second jaw means; said blade means first end being hook-shaped for insertion between the insulation and the conductive portion of an insulated conductor cover means disposed over at least said first end of said blade means and coupled to said selective one of said first and said second jaw means; and means cooperative with said blade means for biasing said blade means in said first position.

2. The improvement as defined in claim 1 wherein said cover means comprises a housing portion, said hi asing means being located within said cover means housing portion.

3. The improvement as defiined in claim 2 wherein said cover means housing portion further comprises support means for maintaining said biasing means in a predetermined position.

4. The improvement as defined in claim 1 said blade means further comprising stop means releasably engageable with said cover means when said blade means is in said first position.

5. The improvement as defined in claim 1 wherein said biasing means comprises spring means.

6. The improvement as defined in claim 5 wherein said spring means is a compression spring.

7. The improvement as defined in claim said spring means is an extension spring.

8. The improvement as defined in claim 1 wherein said blade means comprises a second end selectively formed to provide a finger support therefore.

9. The improvement as defined in claim 8 wherein said finger support comprises a leg portion integral with and extending outwardly from the surface of said blade means.

10. The improvement as defined in claim 9 wherein said leg portion is disposed generally normal to the surface of said blade means.

11. The improvement as defined in claim 1 wherein said blade means has a slotted portion, and said tool comprises fastening means having a shank portion extending through said blade means slotted portion for guiding said blade means between said first position and said second position.

12. The improvement as defined in claim 1 wherein said cover means further comprises a lip portion at least partially encompassing said blade means first end. l= l l 5 wherein

Patent Citations
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3965777 *Sep 29, 1975Jun 29, 1976Mcmillan Charles GBroken needle removal tool for knitting machines
US4198751 *Dec 11, 1978Apr 22, 1980Egbert Lawrence ESkinning knife
US4344230 *Aug 27, 1981Aug 17, 1982Olander Donald ALeather tooling apparatus
US4387746 *Mar 14, 1980Jun 14, 1983Slater Electric Inc.Wire separation tool and method of preparing multiconductor cable
US4797988 *Mar 27, 1986Jan 17, 1989Slater Electric, Inc.Method and tool for preparing multi-conductor cable
US4953248 *Feb 2, 1990Sep 4, 1990Trombetta Thomas LElectrician's compound tool
US5203083 *Feb 5, 1992Apr 20, 1993Domonoske Dean DCutting device
US6029297 *Jun 19, 1998Feb 29, 2000French; Thomas J.Multi-purpose electrician pliers tool
US8739412 *Apr 23, 2008Jun 3, 2014Constantine M. GioiaUtility knife blade
US20040159197 *Feb 13, 2003Aug 19, 2004Kevin ForsbergApparatus and method for cutting cables and wires
US20070289137 *Jun 18, 2007Dec 20, 2007John Robert EgazarianPackage opener
US20080295344 *Apr 23, 2008Dec 4, 2008Gioia Constantine MUtility knife blade
WO1991011296A1 *Jan 23, 1991Aug 8, 1991Thomas L TrombettaElectrician's compound tool
Classifications
U.S. Classification7/107, 30/162, D08/98, 30/90.4, 30/317, 7/132
International ClassificationH02G1/12, B25B7/00, B25B7/22
Cooperative ClassificationH02G1/1217, B25B7/22
European ClassificationH02G1/12B2B4, B25B7/22