WO2011091034A1

WO2011091034A1 - Scoring and slitting hand tool

Info

Publication number: WO2011091034A1
Application number: PCT/US2011/021713
Authority: WO
Inventors: Fuhua Ling; Erik Olson
Original assignee: Tyco Thermal Controls Llc
Priority date: 2010-01-19
Filing date: 2011-01-19
Publication date: 2011-07-28
Also published as: GB2489152A; GB201211662D0; CA2786309A1; DE112011100281T5

Abstract

A sheath cutting and slitting hand tool for cutting and slitting a cable sheath of a cable includes a handle portion adapted to be grasped by the hand; a head portion extending outwardly from the handle portion and exposing a sheath scoring blade for scoring a plastic sheath to a controlled depth less than a nominal thickness of the sheath. The tool further includes a sheath engaging and slitting edge for engaging, spreading and slitting the plastic sheath lengthwise when the handle portion is grasped and drawn along the sheathed body from a cut of the sheath made by the sheath scoring blade.

Description

SCORING AND SLITTING HAND TOOL

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates generally to hand tools for scoring, slitting and stripping insulating polymeric cable jackets from sheathed electric cables, strip heaters, and the like.

Background of the Invention

While there is a wide variety of cable stripping hand tools presently available, generally most of them have not been found to work well for stripping the jackets of self-regulating heating cables. Therefore, general purpose utility, craft or pocket knives have frequently been used for stripping off protective jackets of such cables to enable access to, and electrical connections to be made to, an underlying metal braid layer and to the electrical conductors of the heating cable. While these general purpose cutting tools have been known and widely used for many years, a high level of user skill and experience is required to use such tools safely and successfully, particularly without causing scoring, cutting or other unwanted damage to the underlying metal braid layer, inner jacket layer, polymer core or the conductors themselves. For example, when using a general craft knife or pocket knife it is easy to score and damage the underlying braid layer while cutting through the outer sheath or jacket, since there is no effective regulation of cutting depth other than the skill of the knife's user. In some instances the conductors may be damaged while scoring the inner jacket. In addition, there remains a high risk of personal injury to the user from inadvertent cutting because of the exposed cutting blade edge, which can be relatively large when conventional general purpose knives and hand tools are used. Specialized tools have been proposed for cable slitting. For example, U.S. Pat. No. 4,433,484 to Antisdel et al. entitled "Cable Stripper" shows an elongated two-part tool using standard razor blades. One of the blades is exposed within a groove at one end of the tool for scoring the cable jacket, while another blade is exposed within a hook portion at an opposite end of the tool. The hook portion does not include any contouring to aid separation of the cable edge during slitting. Also, the cable scoring blade edge is directly exposed to the user, and the indicated manner of use has the user's thumb placed nearly or directly over the cable scoring blade during the sheath scoring operation, leading to potential injury to the thumb.

Another tool for stripping a cable is illustrated in U.S. Pat. No. 4,189,799 to Litehizer, Jr., entitled "Cable Stripping Tool". The disclosed device includes blades for penetrating and tearing off the cable sheath and then for stripping insulation off of ends of individual wires of the cable. The insulation jacket is not always completely removed at the cable end being prepared for connections.

A fairly complicated and expensive two-part tool for stripping cable jackets and wire insulation is shown in U.S. Pat. No. 5,337,479 to Ducret, entitled "Cable and Wire Stripper". This particular tool includes a thumb screw enabling adjustment of cutting depth of the blade used for both scoring and slitting, but does not appear to have a size or overall shape which facilitates easy or comfortable grasping in the use's hand during usage.

Another hand-held tool for stripping off a plastic sheath covering a cable is described in U.S. Pat. No. 5,142,780 to Brewer, entitled "Electric Cable Stripping Tool with Claw". This tool includes a dulled claw which is used to pierce through the outer plastic sheath, and a crescent shaped blade edge including a parting shoe to facilitate slitting operation. Neither the claw nor the crescent shaped blade is effectively shielded to protect the user from being inadvertently cut or punctured.

Other hand-held tools for stripping off cable sheaths are shown for example in U.S. Pat. No. 3,946,487 to Bieganski, entitled "Tools for Cutting"; U.S. Pat. No. 3,881,249 to Cox, Jr., entitled "Cable Stripper"; U.S. Pat. No. 4,472,877 to Undin et at., entitled "Tool for Removing Insulation from Cables"; U.S. Pat. No. 4,081,871 to Knuth, entitled "Electrician's Wire Stripping Tool"; and U.S. Pat. No. 4,426,778 to Christie, entitled "Device for Stripping Wire and Cable". A tool head for an automated cable stripper is shown in U.S. Pat. No. 4,543,717 to Luka, entitled "Cable Stripper".

One particularly useful tool has been disclosed in U.S. Pat. No. 6,510,611 to Edwards et al, entitled, "Cable Jacket Stripping Tool". This tool, however, does not provide many of the advantages of the present invention.

While such prior approaches appear to have been reasonably effective for their intended purposes, they were not without drawbacks. Some of the approaches featured and/or required custom blades, or special mechanisms and arrangements enabling the blade to be moved into cutting position or adjusted for cutting depth, or retracted after use. Some did not inherently provide any protection against unwanted exposure to cutting during use or handling. And, many of the prior approaches did not combine the features of relative simplicity, ease of manufacture at low cost, ease of use, or other useful feature into a single hand-held cutting instrument. SUMMARY OF THE INVENTION

This invention relates to improvements in hand-held devices for stripping polymeric jackets of cables, such as electrical power cables, communications cables, fiber optic cables and self-regulating heating cables. An elongated, gripable sheath scoring and slitting hand tool of the present invention provides an improved device for scoring and slitting cable. The tool includes a covered sheath-scoring blade for radially scoring a plastic sheath when the handle portion is grasped in the first orientation, two blades along the sides of the tools for engaging, spreading and slitting the plastic sheath lengthwise when the handle portion is grasped in a second orientation, and a core slitting blade.

The present invention provides a safe, accurate and easy means of stripping insulation and core materials, among others, to expose conductive wires in cables of many kinds, such as for heating, power, data, signal, and other like cables. The invention provides a cutting blade(s) having a controllable and fixed exposed blade depth that maintains an accurate and consistent slit depth(s). The blade depth(s) is preferably set for typical cables, and can be easily adjusted for other non-standard cables. The fixed blade depth makes it easy to follow the contour of the cable and prevents the blade from accidentally cutting the user.

Hand tools in accordance with the present invention are particularly useful for stripping the polymeric protective and insulating jackets of self-regulating heating cables of the type sold by Tyco Thermal Controls, of Menlo Park, California. Self-regulating heating cables frequently have unique cross-sectional shapes and multilayer construction. The tools of the present invention may be used with self-regulating heating cables of a broad range of sizes, shapes and jacket materials.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in the accompanying drawings, in which:

FIG. 1 is a side view of a sheath scoring and slitting hand tool in accordance with principles of the invention;

FIGs. 2A-2C are side view drawings of the sheath scoring and slitting hand tool shown in

FIG. 1;

FIGs. 3A-3D are drawings representing different positions of the head portion of the sheath scoring and slitting hand tool;

FIGs. 4A-4C are drawings representing various embodiments of the cutting members of the head portion of the sheath scoring and slitting hand tool;

FIGs. 5A-5C are representations showing different cutting processes using the sheath scoring and slitting hand tool;

FIG. 6 is a drawing showing extension of an internal blade compartment of the sheath scoring and slitting hand tool; and,

FIG. 7 is an isometric view showing axial separation and removal of a sheath segment which has been radially scored and cut, and longitudinally slit in accordance with the operation shown in FIGs. 5.

DETAILED DESCRIPTION OF THE INVENTION

A scoring and slitting hand tool 100, shown in FIG. 1, includes a body 102 having an elongated, gripable handle portion 128 and head portion 108. The scoring and slitting hand tool 100 is used for preparing heating cables for the purpose of making an electrical connection.

The handle portion 128 is sized to be grasped comfortably in the hand of an adult user and extends along a longitudinal axis 200 of the body 102. The handle portion 128 merges into the head portion 108 which also extends along the longitudinal axis 200. In addition to being gripable, the handle portion 128 optionally incorporates at least one opening 114 at a distal end from the head portion 108 to enable the tool 100 to hang on a hook of a tool rack or user's belt. As further seen in FIG. 1, the sheath scoring and slitting hand tool 100 preferably includes an extendable compartment 104 (as further detailed in FIG. 6) integral in the body 102 and accessible the distal end of the handle portion 128. At this end, the handle portion 128 also retains a core slitting blade 132. Preferably, the length of the handle portion 128 of the body 102 is from about 3 inches to about 5 inches long. Additionally, the handle portion 128 of the body 102 may be configured for appropriate hand grasping and manipulation, such as contoured, straight, indented or other like forms for hand use.

The head portion 108 of the body 102, shown in FIG. 1, includes a multi-depth cutting 126 device. The cutting device 126 has a first cutting end portion 122 having a first cutting depth and a second cutting end portion 124 having a second cutting depth that is distinct from the first cutting depth for radially scoring a plastic sheath of a cable when the handle portion 128 is grasped in a first orientation. In this regard several preferred embodiments are available as detailed in FIG. 4.

Referring to FIG. 2, the present invention includes a similar configuration on opposite sides of the body 102, shown in FIGs. 2A and 2C, and a narrow dimension, as seen in FIG. 2B. As seen in FIG. 2B, the multi-depth cutting 126 device includes a rotating cover 110/112 having a first side 110 and second side 112 adjacent to, and on the side of, the first cutting end portion 122 and second cutting end portion 124. Referring to FIG. 3, several positions of the rotating cover 110/112 are shown. In FIG. 3 A, the rotating cover 110/112 is in a first position covering both the first cutting end portion 122 and second cutting end portion 124. As such the user is protected from inadvertent injury from an exposed blade. In FIGs. 3B and 3C, the rotating cover 110/112 is in a second and third position, with each position exposing the first cutting end portion 122 for cutting operations. In FIG. 3D, the rotating cover 110/112 is in a fourth position exposing the second cutting end portion 124 for cutting operations. The rotating cover 110/112 preferably includes a generally semicircular shaped cover pivotally mounted to the head portion 108 and covering part or all of one or both blade depths of the cutting blade when in a closed position. When locked, for example, molded cylindrical or hemispherical projections of the rotating cover 110/112 mate with aligned recessed cylindrical openings in the head portion 108 thereby enabling the rotating cover 110/112 to be snap-locked onto the head portion 108 while permitting the rotating cover 110/112 to then be rotated by the user to alternately cover the cutting blade 110 while exposing the cutting blade 112. When the cutting blade 112 is not being used, the cover is positioned over the blade 112 in order to provide protection to the user against accidental cutting. Preferably the rotating cover 110/112 includes a rotational transfer axis effective to rotate the rotating cover 110/112 from a first position covering one of the first and second cutting depths to a second position covering the other first and second cutting depths. In this, or similar, configurations, the rotating cover 110/112 may include a cover spring configured to allow the cover to rotate with a cutting action of the hand tool 100, and expose one of the cutting depths and then automatically return the cover to a position safely covering the blades. Additionally, the cover may be locked in any given position, preferably, in one of three locked positions of (1) an exposed first blade, (2) an exposed second blade, or (3) both blades covered. Preferably the cover automatically rotates to a protected position.

Referring to FIG. 4, in one preferred embodiment shown in FIG. 4A and 4B, the head portion 108 of the present invention includes two separate blades of the first cutting end portion 122 and second cutting end portion 124 having different blade depths for scoring the cable jacket. Alternatively a single cutting blade 122/124 has a convexly curved cutting edge lying generally on both sides of the axis 200 and presenting distinct cutting depths on either side of the axis 200. Preferably the curved surface of the cutting blade 122/124 includes a shoulder 118 which is spaced away from, and most preferably follows, the contour of the curved cutting edge 122/124 in a manner to provide the different cutting depths. The distance between the shoulder and the curved blade edge of the cutting blade 122/124 is selected to limit the depth of cut to the thickness of a plastic sheath of a cable to be cut, and also provides some protection to the user of the tool 100 to prevent accidental cutting to an operator. Preferably, the shoulder 118 slightly tapers away from the edge of the cutting blade 122/124. In another alternative embodiment, a single blade of uniform circumference, shown in FIG. 4C, may be offset within the head portion to provide two distinct cutting depths. Of the several embodiments of the cutting blade 122/124 having at least two distinct cutting depths, (i) a contoured single blade forming at least the first and second cutting depths, (ii) an offset single blade forming at least the first and second cutting depths, and (iii) multiple blades forming at least the first and second cutting depths, most preferably multiple blades forming two distinct cutting depths is used. This single sheath scoring blade 122/124 establishes a predetermined maximum scoring and cutting depth, set to correspond generally to the thickness of a cable sheath layer to be scored, along one part of the blade with a second predetermined maximum depth to correspond generally to a second thickness. The rotating cover 110/112 effectively covers the scoring blade 122/124 to protect the user from being cut accidentally. In accordance with one aspect of the present invention, the cutting blade comprises a standard craft blade, such as an X-acto.TM.#10 blade made by Hunt Manufacturing Corporation, Statesville, North Carolina, or #10 Hobby Blade made by Techni- Edge Manufacturing Corp, Little Ferry, New Jersey, or equivalent.

As seen in FIGs. 1 and 4A, the head portion 108 includes two slitting blades 106 located on opposite sides of the body 102 for engaging, spreading and slitting the plastic sheath of the cable lengthwise. These blades 106 are used, shown in FIG. 5B, when the handle portion 128 is grasped and drawn along the sheathed cable from a score line of the sheath made by the sheath scoring blade 122/124. In this regard the sheath slitting blades 106 include a slitting blade having a generally straight slitting edge forming an oblique angle from longitudinal axis 200 along, and facing back to, the handle portion 128. This oblique angle, as shown in FIG. 4A, preferably includes an angle Θ of from about 45° to about 90°, more preferably, from about 60° to about 85°. As such, the slitting blades 106 are used when the hand tool 100 is turned to a second hand orientation, shown in FIG. 5B, from the first hand orientation, shown in FIG. 5A, when the hand tool 100 is being used to score the plastic sheath of the cable to a controlled depth slightly less than the sheath thickness along a radial score line with the sheath scoring blade 122/124. Each slitting blade 106 is adjacent to a respective contoured sheath-guiding and spreading tip 107 contoured to resemble a hook or plow. This sheath-guiding and spreading tip 107 guides the slitting blade 106 along the cable sheath during a lengthwise slitting operation. The sheath guiding and spreading tip 107, located at an outer end of the slitting blade 106, engages the underside of the cable plastic sheath and spreads apart facing edges of this cable sheath undergoing slitting by the slitter blade 106 as the hand tool 100 is drawn along a length of cable during a cable slitting operation. Once slit, the plastic jacket can then readily be removed. The slitting blade 106 most preferably comprises a standard craft blade, such as an 0.35" snap blade made by Techni-Edge Manufacturing Corp., Little Ferry, New Jersey, or equivalent.

A core slitting blade 132, shown in FIG. 2B, is located at the base of the hand tool 100. The core slitting blade 132 is used to slit the edge of the polymeric core in order to expose the bus wires. The core slitting blade 132 has a fixed cutting depth within a u-shaped channel 133 for positioning the cable core for effectively cutting the core. As seen in FIG. 5C, the cable core is placed within this channel 133 and longitudinally pulled across the internal blade to slit the core. Preferably there is an extendable compartment 104 integral in the body of the tool 100 accessible at the distal end of the hand tool 100, as shown in FIG. 6. Referring to FIGs. 1 and 6, most preferably, the core slitting blade 132 is fixed at the end of this extendable compartment 104. This extendable compartment 104 may be configured to house additional blades 150 or other spare parts, replacement blades, and the like useful in the manipulation of cables.

Referring to FIG. 7, in operation, the heating cable 130 is scored around a selected cross- section with the first cutting depth corresponding to the thickness of the outer polymer jacket 160. Once the cable 130 has been scored along the scoring line 168, the cable is flexed back and forth several times. This bending or flexing operation causes the outer jacket 160 to become completely severed along the score line. The hand tool 100 is repositioned within the user's hand, and the guiding and spreading tip 107 is inserted beneath the outer jacket 160 and above the braid layer 166 at the scored line with the outer jacket 160. The outer polymer jacket 160 of the cable 130 is then slit 164 with the hand tool 100 to prepare the cable for making an electrical connection. The tool 100 is drawn by the user along the cable 130 while the cable 130 is maintained in a stationary position, causing the outer cable jacket 160 to be slit along a slit line 168. Once the segment of cable jacket 160 is completely slit open along its longitudinal extent, the tool 100 is put down, and the user may then grasp and further separate the severed and slit segment 168 of cable jacket 160 from the underlying braid layer 166. The outer jacket 168 is removed and braid 166 is moved to allow scoring around an inner jacket of the heating cable core with the second cutting blade of the hand tool. The inner jacket is removed, exposing the conductive core of the cable for further cable end preparation steps as may be needed to complete a particular cable connection operation.

Those skilled in the art will appreciate that many changes and modifications will become readily apparent from consideration of the foregoing descriptions of preferred embodiments without departure from the spirit of the present invention, the scope thereof being more particularly pointed out by the following claims. The descriptions herein and the disclosures hereof are by way of illustration only and should not be construed as limiting the scope of the present invention.

Claims

What is claimed is:

1. A scoring and slitting hand tool for preparing heating cables for the purpose of making an electrical connection, comprising:

a handle portion of the body adapted to be grasped by the hand; and,

a first cutting end portion of the body having at least a first cutting blade forming a first cutting depth and a second cutting blade, the first cutting end portion having a second cutting depth distinct from the first cutting depth.

2. The sheath scoring and slitting hand tool of claim 1, further comprising an extendable compartment integral in the body.

3. The sheath scoring and slitting hand tool of claim 1, further comprising a single blade to form at least the first and second cutting depths.

4. The sheath scoring and slitting hand tool of claim 3, wherein the single blade adjusts to form the at least the first and second cutting depths.

5. The sheath scoring and slitting hand tool of claim 3, wherein the single blade is offset within the body to form the at least first and second cutting depths.

6. The sheath scoring and slitting hand tool of claim 1, further comprising the first blade having the first cutting depth and a separate second blade having the second cutting depth.

7. The sheath scoring and slitting hand tool of claim 1, further comprising a cover for covering at least a portion of the first cutting end portion.

8. The sheath scoring and slitting hand tool of claim 7, wherein the cover includes a rotational axis for rotating the cover from a first position covering at least one of the first and second cutting blades to a second position exposing at least one of the first and second cutting blades.

9. The sheath scoring and slitting hand tool of claim 1, further comprising a rotating cover configured to rotate the cover with a cutting action of the hand tool, and exposing one of the cutting blades.

10. The sheath scoring and slitting hand tool of claim 1, further comprising a spring-loaded rotating cover that includes a safe set resting position wherein the cutting blade surfaces are covered.

11. The sheath scoring and slitting hand tool of claim 1 , further comprising at least a first lateral slitting blade.

12. The sheath scoring and slitting hand tool of claim 11, further comprising at least a second lateral slitting blade. The sheath scoring and slitting hand tool of claim 11, further comprising at least a first lateral blade guide tip.

13. The sheath scoring and slitting hand tool of claim 2, wherein the extendable compartment is configured to store a spare blade.

14. The sheath scoring and slitting hand tool of claim 1, wherein the length of the handle portion of the body is from about 2 inches to about 5 inches long.

15. The sheath scoring and slitting hand tool of claim 1, further comprising a core slitting blade.

16. The sheath scoring and slitting hand tool of claim 16, wherein the core slitting blade has a controlled cutting depth and orientation relative to the core cross-section for cutting.

17. A method for scoring and slitting cable sheath, comprising the steps of:

providing a scoring and slitting hand tool for preparing heating cables for the purpose of making an electrical connection having a handle portion of the body adapted to be grasped by the hand and a first cutting end portion of the body having a first cutting depth and a second cutting depth distinct from the first cutting depth;

scoring around a selected cross-section of a heating cable with the first cutting surface no deeper than the thickness of the outer polymer jacket;

displacing a length of the outer jacket;

moving braiding that was below the displaced length of the outer jacket;

scoring around an inner jacket of the heating cable with the second cutting depth; and, displacing the inner jacket wherein the heater core is exposed.

18. The method of claim 18, further comprising the step of longitudinally slitting the outer and inner jackets with a lateral cutting blade.

19. The method of claim 18, further comprising the step of slitting the exposed heater core.