US 3769705 A
A device for precisely and squarely cutting a length of insulation or shielding about a wire preparatory to stripping it from a cable, comprising a body member having a bore into which the cable is inserted and supported, a cutting element secured to a frame bearingly mated to the body member and which is adapted to communicate with such bore, means for biasing the frame and cutter in a direction for the cutter to engage the insulation about the wire, and a micrometer mounted in fixed spaced relationship to the body and which provides in its calibrated adjustment and operation for varying the exact degree or extent of movement or displacement for the frame and cutter as the cutter slices into the insulated cable. The setting of the micrometer limits the extent of movement of the frame and cutter in relation to the body member and its bore. The biasing means is adjustable to effect the desired tension on the material of the insulation. Scale means is provided to determine the length of the cable to be inserted into the body and by which a length of insulation is determined to be cut. The cutter performs a slicing action across the insulation as the device is turned about the cable and in accordance with the tension provided by the adjustable biasing means, to effect a clean and true or square cutting of a layer of insulation or shielding to an exact depth. Adaptors or bushings are provided for the body for supporting a variety of sizes of insulated cables.
Claims available in
Description (OCR text may contain errors)
United States Patent 1 Biddle NOV. 6, 1973 WIRE STRIPPING DEVICE  Inventor: James A. Biddle, Sepulveda, Calif.
 Assignee: Lockheed Aircraft Corporation,
- Burbank, Calif.
 Filed: Dec. 20, 1971  Appl. No.: 210,024
Primary Examiner-Othell M. Simpson Assistant Examiner-J. C. Peters Attorney-Frank L. Zugelter  ABSTRACT A device for precisely and squarely cutting a length of insulation or shielding about a wire preparatory to stripping it from a cable, comprising a body member having a bore into which thecable is inserted and supported, a cutting element secured to a frame bearingly mated to the body member and which is adapted to communicate with such bore, means for biasing the frame and cutter in a direction for the cutter to engage the insulation about the wire, and a micrometer mounted in fixed spaced relationship to the body and which provides in its calibrated adjustment and operation for varying the exact degree or extent of movement or displacement for the frame and cutter as the cutter slices into the insulated cable. The setting of the micrometer limits the extent of movement of the frame and cutter in relation to the body member and its bore. The biasing means is adjustable to effect the desired tension on the material of the insulation. Scale means is provided to determine the length of the cable to be inserted into the body and by which a length of insulation is determined to be cut. The cutter performs a slicing action across the insulation as the device is turned about the cable and in accordance with the tension provided by the adjustable biasing means, to effect a clean and true or square cutting of a layer of insulation or 10 Claims, 4 Drawing Figures PAIENIEDuuv s 1915 SHEET 2 BF 2 FIG. 3
WIRE STRIPPING DEVICE BACKGROUND OF THE INVENTION 1. Field of the Invention Conventional practice in stripping insulation from an electrical conductor has included both manual cutting with a knife and other instruments. In the assembling of electrical circuits required in avionic mechanisms utilized in aircraft today, for example, a device for cutting the insulation of a small sized cable must adequately perform the important function of precisely and squarely cutting one or more layers of such insulation or shielding, from either a coaxial cable or other cable, in order to achieve a clean exposure of wireof a given length preparatory to making a precision contact for it with other similar wires in the mechanism being assembled. The space limitations required of these avionic devices require that the least quantity and smallest sizing of electrical cable circuitry be utilized; Also, the assembler must work with cables having short and accurate lengths of exposed wire for a snug positioning in sucha mechanism. Thus, a device for precisely and squarely cutting through a layer of insulation or shielding at a given point along the length of a small .sized cable would accomplish these objectives. My invention does so.'
2. The Prior Art Examples of prior art wire stripping instruments which have been known prior to this' invention are found in the disclosures of the following US. letters Pat. Nos. 3,378,924; 3,304,605; 3,169,315; 2,955,494; 2,903,064; 2,871,739; 2,863,158; 2,817,255; 2,752,676; 2,683,930; 2,695,537;
PROBLEMS IN THE PRIOR ART SUMMARY OF THE INVENTION This invention relates to a device for cutting insulation or shielding comprising one or more layers froman electrical cable, coaxial or otherwise, and ordinarily referred to as a wire stripping device, and is particularly directed to a device for cutting one or more of such layers provided on a coaxial cable or the like preparatory to physically stripping such layers cut thereby from the remainder of the cable.
An object of this invention is to provide an efficient and speedy cutting of one or more of such layers on a cable preparatory to stripping it from such wire.
A further object of this invention is to provide for a slicing cutting action upon and to an exact depth in the layer. as distinguished from other forms of cutting action, in order to completely eliminate the nicking of the 2,721,833, 2,452,734; 2,300,087; 1,763,299; and 1,566,297.
Another object of this invention is to provide a true or square cutting upon the layer in the operation of the device thereon.
Another object of this invention is to reduce the time consumed in wire stripping which heretofore has been routinely involved in the preparation for stripping one or more such layers from a cable, thereby reducing the total number of manhours to work therefrom and the cost ofsuch work.
Another object of thisinvention is to provide a precise depth of penetration to any desired extent or degree in the slicing action of the cutting device, such penetration corresponding to the exact radial or thickness dimension of the layer being severed.
Another object of the invention is to provide a precise cutting ona greater variety of sizes of insulated cable than realized previously, with only one device.
A still further object of the invention is to provide an economical and efficient device,'one which is compact in nature and size, withminimum number of parts, and easily assembled and operable.
An object of this invention is to provide a cutting of one or more of such layers from a cable, coaxial or otherwise, without nicking or damaging the wire conductor or other layers in the cable.
.Another object of this invention is to provide a variable tension on a cutting element applied to the layer, depending upon the nature of the material constituting such layer, be it rubber or fibrous, so that a clean cutclearly through such material.
A further objectof the invention is to provide a support for the cables length as a layer is severed, eliminating axial movement of the cable and its insulation or shielding during the cutting operation.
Another object of this invention is to provide a way to eliminate axial movement of the insulated cable during the cutting operation thereon, thereby ensuring atrue and square cut to the cut layer.
' These and other objects of this invention will become fully apparent from a reading of the following description of the preferred embodiment of the invention, the
- appended'claims thereto, and the accompanyingdrawing.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an exploded perspective view of the pre- 7 ferred embodiment of the invention.
wire which otherwise damages the wire in its electrical installation, and to eliminate frayed or hanging particles of the layer to either side of the plane of cutting.
FIG. 2 is a plan viewof the preferred embodiment of the invention in its assembled condition.
Fro-3 isaview taken on line 3 3 of-FIG. 2.
FIG. 4 is a view taken on line 44 of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing in which reference characters correspond to the following numerals, reference characters 10 (FIGS. 2, 3 and 4) refers generally toa wire' stripping device constituting an embodiment longitudinally included in the body 13 for introduction and support of an'insulated cable to be stripped, a micrometer 16 mounted on a base member 17 secured to the body 13 for cooperative action with the frame 12, a cutting means 18 accommodated in openings provided in the frame 12 and the body 13 in such a manner as to communicate with the'bore of the body 13, a means 20 for biasing the cutting element to its maximum point or plane of penetration in the bore 15, and a scale means 22 for determining a given length of insulated cable to be inserted and cut of one or more of its layers.
The frame 12 comprises a continuously formed foursided, metal member having longitudinally disposed open opposing faces into the frontal one of which, the body 13is slip-fitted. The body 13 includes opposing bearing faces 24 each of which physically rectilinearly engages its associatedinner wall 25 of the frame 12 l2 and body 13 are longitudinally secured together by their metal bearing surfaces, they are capable of rectilinearly moving in lateral relationship to each other; i.e., in a lateral direction with respect to the longitudinal axis of the bore 15 in the body 13.
The body 13 preferably includes at the terminus of the bore 15 the start of a countersunk bore 29 extending into and through the handle 14, for relieving any tension which might be induced on the length of thelayer of insulation or shielding of the cable in the device l0. 7 I
The base member 17 conveniently provides a'manner for mounting the micrometer 16 in a fixed spaced relation to the body 13. It includes an integrally formed elbow 30 from which an arm 32 is developed in parallel positioning of micrometer 16 sets the maximum and an accurate depth to which a cut can be made into an insulated cable, in a given operation of device 10, by limiting the return of the frame 12. The readings on the micrometer 16, of course, may be measured in terms of the readable depth of the cut.
The cutting means 18 comprises a thin, flat metal backing sheet 39 to which a metal blade 40 having a cutting edge 42 is suitably secured, such as by a screw 43 threaded through the blade 40 and through a punched-out, threaded aperture in sheet 39. A stop 44, preferably in the form of a spot-welded bar (FIG. 1), prevents the blade 40 from rotating about sheet 39 during operation of the device 10'. The sheet 39 includes integrally formed and bent apertured tab 45 at its opposite ends for providing a convenient way to secure the cutting means 18 to the frame 12, such as by screws 46. A slot-like opening 48 is formed in a side 49, opposite side 33, and through the.upper and lower sides of the frame 12, for disposition of the cutting means 18 within the frame 12. The blade 40 is thus conveniently accommodated in the slot-like opening 48 which extends preferably to more than halfway of the width of the frame ting edge 42 may be disposed in, preferably an extenspaced relation to the one side 33, (FIG. 3) of frame 12. r
The micrometer l6is suitably mounted to the arm 32 by means of a shaft 34 suitably secured to its' one end and threaded in an aperture provided inthe arm 32. A nut 35 is provided on the shaft 34, to bear against arm 32 for securing a particular adjusted position for the micrometer 16. Such securement calibrates out the accumulated tolerances existing between a device 10 and another. In other words, it is merely a calibrating device or technique to ensure that each'device 10 will cut in exactly the same manner as the next tool.
The other end of the micrometer 16 includes an operable rod 36 cooperatively related to the one side 33' of the frame 12 (FIG. 3). The spring-and-Allen-screw' combination 20 mounted in appropriate facing apertures in body 13 and side-33, respectively, biases the frame 12 towards the micrometer l6 and itsoperating rod. 36. Conversely, the abutment of the rod 36 against the frames side 33 affects the lateral disposition of the frame 12 relative to the body 13. Adjustment of the micrometer 16, therefore, laterally displaces the frame 12 body 13 prevents axial displacement of each bushing sion 52' of narrower width in, slot 50 which extends to the axis of bore 15 in body 13. This slot extension 52 should fit the blade thickness to prevent its deflection in the operationof the device 10. Thus, upon securement of the cutting means 18 to the frame 12, the frame 12 to the body 13 and the biasing means 20 thereto, the cutting edge 42 is disposed at the plane of such axis. Adjustment of theposition of the micrometer 16, of course, displaces the edge 42 therefrom in a lateral direction opposite. to the direction of the biasing effect of the means 20 and/or the location of the micrometer 16.
- The preferred embodiment of the device 10 includes a plurality of bushings 54 any one of which is slip-fitted to the bore 15. Each bushing 54 has a different sized bore to support a corresponding sizedcable to-b'estripped. An annular slot 56 is provided'in each bushing 54 for alignment with the slot extension 52 in body 13, and mutually cooperating flats 48 (FIG. 1). are provided on flanges respectively included in body 13 and each bushing 54 for ensuring such alignment by preventing rotation of the bushing in the bore 15. A set screw 60 (FIG. 1) insertable through the frame 12 and 54 in the bore 15. a
The scale means 22 includes a graduated linear unit arrangement preferably in 1/100 inch gradations, provided in parallel alignment to the bore 15 for measuring a length of cable, from its end, which is to be stripped of its layer or layers. A finger 6.1 with a hole 62 therein in axial alignment with the bore 15 is preferably provided on scale means 22 for marking the cable in resuitable manner in a keyway 64 provided in the bottom of handle 14 (FIG. 4).
Assembly of device should be apparent from the above description, however, briefly, the body 13 is introduced into the frame 12 and aligned with the base member 17 so that the screw 26 project through the member 17, and are secured to body 13. The cutting means 18 is first assembled and then inserted in the slot-like opening 48 and secured in position to the frame 12 by the use of the tabs 45. The biasing means 20 may then be assembled to the frame 12 and the body 13, as shown in FIGS, and this, of course, should bias the cutting edge 42 to its greatest point of penetration in the bore 15. The micrometer 16 together with its adjusting screw-and-nut 34, 35 are mounted to the arm 32 so-that the operating rod 36 is adapted to physically abut side 33. The scale means 22 is readily mounted to its keyway 64 in the handle 14. Any one of a number of varied-sized bushings 54, for a cable of a desired outer diameter (O.D.), is inserted into bore and secured therein by the set screw 60, however, in order to insert a bushing 54 without interference from cutter 40, which projects into the bore 15, side 33 may be manually thumbed and pushed away from arm 32; i.e., causing side 33 to move closer to body 13. As this is done, cutter 40, secured to frame 12, is removed or retracted from the bore 15 of body 13.
The micrometer 16 is of the type made and sold by the Brown and Sharpe Mfg. Company, Centredale, R.I., under its Model No. 599-263, and is readily available in the marketplace. The blade 40 is preferably an Exacto type of blade commercially available. Such a blade is sold in the form of a strip, a suitable number from which is readily removed from its scored lines forming a demarcation for each Exacto blade, and which is to be utilized as a blade 40 in device 10. A double honed edge is preferred, as a single honed edge may possibly start a threading action on and about the layer.
In operation, device 10 is first calibrated by adjustment of nut 35 on shaft 34. A given sized bushing 54, corresponding to a given sized cable having, say, three layers of insulation each of which is to be stripped from the wire at a different length from its end, is inserted in and secured to the bore 15 by the screw 60. The blade 40 has been removed from the bore 15, as described above, in order to introduce the bushing 54. v
The'micrometer 16 is set to a desired reading corresponding to the maximum extent of introduction desired for the knife edge 42 in the bore 15. The scale means 22 is adjusted to its fully extended position whereby its zero marking 63 is located at the outer wall of the base member 17. Thereafter, the insulated cable is inserted through the hole 62 providedgon the scale means 22 and into the bore of the bushing 54, the end of it abutting the blade 40 in the bore is. The cable is now marked at the hole 62, after which the scale means 22 is readjusted inwardly, say, for example, a distance of 0.25 inch, which is equivalent tothe length of the first or innermost alyer of insulation to be cut from the cable's end. The side 33 of the frame 12 is then thumbed in a lateral direction away from the micrometer 16, i.e., against the biasing effect of means and toward the body 13, so that the bore of bushing 54 is free fromthe blade 40. The cable is now further introduced into the bore 15 until the marking placed on it is once again in alignment with the hole 62 on the scale means 22. This step ensures that a 0.25 inch length of insulation will be cut by the operation of the device l0.
To continue, the side 33 is now released of the grasp of the operator so that the biasing effect of means 20 causes the blade 40 to now engage the outermost layer of insulation of the cable. It is to be noted that the side 33 of the frame 12 and the operating rod 36 of the micrometer are not in physical abutment with each other. The operator now grasps the insulated cable behind the scale means 22 and with the handle 14, he rotates the device 10 about such insulated cable. This produces a slicing action by the blade 40 and its cutting edge 42 against and into all three layers of insulation. After a few turns of device 10 about the cable, blade 40 has moved into the bore of the bushing 54 to its maximum displacement, as a result of the biasing effect of the means 20 and the stop' for the side 33 of'the frame 12 provided by the operating rod 36. Such maximum displacement has already been determined by the setting of micrometer 16. Further turning of device 10 relative to the insulated cable produces no further cutting or slicing action which would cause nicking or damage to the wire itself. A true (or square) movement for the blade has been provided and which precisely corresponds to the thickness or depth of all three layers of the insulation.
In order to cut a second or middle layer of insulation or shielding, the micrometer 16 is reset to a new measurement indicative of the next maximum extent to which the blade 40 is to be introduced into the bore 15 and which corresponds to the thickness or depth of the second layer of insulation. The scale means 22 is again adjusted inwardly, say, for example, another 0.25 inch distance. Thereafter, side 33 is thumbed toward body 13, thereby withdrawing the blade 40 from the bore of bushing 54, so that the operator may further insert the insulated cable. The extent of such further insertion is again readily measured by realigning the marking on the cable with the hole 62, and, of course, the length of such further insertion is, in this example, a distance of 0.25 inch. Thereafter, the side 33 is released by the operator so that the biasing effect of means 20 again causes the blade 40 to engage the first layer of insulation. The operator again manipulates the device 10 relative to thecable held in hand behind the scale means 2 2, in the same fashion as previously described, in order to produce the desired slicing action of the blade edge 42 on the second layer of insulation, to the maximum extent of displacement for the blade 40 corresponding to the micrometer setting. Thus, the innermost and second layers are cut through, at different I points along the length of the cable, but not the outermost layer. In order to remove the third or outermost layer, the above procedure is again carried out, with the insulated cable having been inserted into the bore of bushing 54 to the extent desired and provided by the inwardly readjustment of the scale means 22. After all the layers have been cut through, the cable is removed from the device 10, and stripping in a conventional or known manner of all such layers at their respective lengths from the end of the cable. The result is a square or true and precise stripping at the desired points along the cable. I
The spring in the biasing combination 20 provides for a slot, even sliding action into the layer; with no effective bite (and thus, no distortion of layer material that might cause material fraying or hanging) into the layer material. The Allen screw in the biasing combination 20, adjustable in nature in the side 33 of the frame 12,
provides for an effective pressure on the layer material, and may be adjusted accordingly depending upon what kind of layer material is involved in a given situation. With device 10, and use of the adaptors or bushings 54, stripping depth in as little as 0.0014 inch steps from 0.0 inch to cut-off depth on a 3/16 inch O.D. cable should be effectively achieved. I
Pursuant to the requirements of the patent statutes, the principle of this invention has been explained and exemplified in a manner so that it can be readily practiced by those skilled in the art to which it pertains, or with which it is most nearly connected, such exemplification including what is presently considered to represent the best embodiment of the invention. However, it should be clearly understood that the above description and illustrations are not intended to unduly limit the scope of the appended claims, but that therefrom the invention may be practiced otherwise than as specifically described and exemplified herein, by those skilled in the art, and having the benefit of this disclosure. 7 v
Therefore, what I claim as patentably novel is:
l. A device for cutting one or more layers of insulameans defining openings in said frame and body and oriented perpendicular to and in communication with said bore,
a cutting means secured to said frame and mounted in said openings and including a cutting edgein communication with said bore,
, means mounted between said body and frame for biasing said frame in a direction causing said cutting means to seek its maximum point of penetration in said bore,
means mounted in fixed spaced relation to said body for limiting the maximum extent of movement in such direction for said frame and cutting means,
whereby upon rectilinear displacement of said frame and cutting means away from said limiting means and against the direction of the biasing of said frame, the cable is insertable into said bore, and upon the return rectilinear movement of said frame in such direction, said cutting edge engages the cables layer, after which the relative turning between said device and cable causes a slicing action of said cutting edge through the cable to a'depth predetermined by the relative position of said lighting means to said frame. 4
2. The device of claim 1 in which said limiting means comprises a micrometer, the abutment of said frame against said micrometer corresponding to the maximum extent of movement of said frame in such direction. I
3. The device of claim 1 including scale means for determining the point along the length of the cable at which the cut is to be made.
4. The device of claim 3 in which said scale means comprises a graduated scale bar adjustable longitudinally of said device, and having means thereon for marking a cable, the marking of such cable and said marking means providing a measurement of a length of the cable to be cut. 7
5. The device of claim 1 in which said biasing means comprises a spring mounted between said body and frame.
6. The device of claim 5 in which said biasing means is adjustable for regulating the tension of said cutting means on an inserted cable.
7. The device of claim 1 including a bushing for said bore whereby a different sized cable for the device than one sized to the bore is insertable and cuttable'by operation of said device. I
8. The device of claim 7 in which said bushing includes a flat, and a second flat is included on said body, both flats mutually cooperating with each other for ensuring alignment of said openings by preventing rotation of said bushing.
9. The device of claim 1 including a base member secured to said body, I
said frame beingdisposed between said base member and handle, I
an arm mounted on said base member is spaced relation to one side of said frame,
said limiting means being fixed to said arm and being cooperatively related to said side of said frame whereby such limiting movement is effected.
10. A wire stripping device comprising in combination,
a body having a bore for supporting a cable having at least one layer of insulation or the like thereon,
a slot in said body and oriented perpendicular to the axis of and in communication with said. bore,
a frame mounted to said body and having an opening therein in alignment with said slot,
said frame and body being rectilinearly slidable relative to each other,
a cutting means including a cutting edge mounted in said opening and secured to said frame, said cutting edge communicable with said bore through said slot,
, means for biasing said frame in a rectilinear manner relative to said body so as to cause said cutting edge to seek its maximum point of penetration in said bore, and
micrometer means mounted in fixed spaced relation to said body-andbeing cooperatively related to said frame for overcoming the directional effect of said rectilinearly-acting biasing means,
whereby adjustment of said micrometer means predetermines the maximum extent of said cutting edge in said bore, and upon insertion of a cable in said bore and operation of said device, said cutting edge severs the insulation or the like thereon to such maximum extent.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,769,705 Dated Nov. 6, 1973' Inventorfiq) JAMES A. BIDDLE It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Col 7, line 52, "lighting, should read ---limiting- 8, line 27 "is" should read ---in----.
Signed and sealed this 23rd day of April 197L (SEAL) Attest;
EDWARD MJ LETCHERJRG C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-1I050 (IO-69) u c go ng-p59 11 ms. GOVIINIIINI' "mills omct nu o-au-ng