Patent Description:
Fiber optic cables are becoming more popular because the distance a signal can travel within a single fiber is far greater than in traditional copper cables. Installing these cables is time consuming because cable preparation is vital to signal strength. The fiber optic cables are very fragile, and any damage could dramatically reduce the performance of the cable. As with any cable network, the need to perform mid-span access is necessary. Mid-span cable preparation is more difficult because you cannot simply slip the cable construction off the end of the cable. Midspan access is common since service loops are used for long cable runs to allow for future expansion and configuration.

Typical fiber optic cable <NUM> construction such as the one shown in <FIG> consists of an outer jacket <NUM> with multiple groups of optical fiber <NUM>. The individual optical fiber strands <NUM> are usually grouped within loose buffer cables or tubes <NUM> to help with cable organization and protection. Loose buffer tubes <NUM> are used in the cable construction and each has a surrounding layer of dielectric insulation <NUM> surrounding the fiber strands <NUM> for protection as well as grouping of subsets of fiber strands. Typically, <NUM> fibers strands <NUM> are bundled into a buffer tube <NUM>. Support or strengthening cable <NUM> may be disposed between the tubes <NUM> to prevent the fiber optics from damage due to tension or compression. The loose buffer tube <NUM> is shown in <FIG> includes outer jacket or insulation layer <NUM> with single fiber buffer tubes <NUM> grouped within the insulation layer <NUM>.

One of the final steps for accessing mid-spanning fiber optics is removing a portion of insulation of the buffer tube around the fiber optic cables to expose the individual signal-carrying fiber strands. Different cable manufacturers use different diameter buffer tubes, causing an installer to purchase and use a different tool for each tube size. Loose buffer tubes are typically <NUM>-<NUM>" thick depending on tube diameter and manufacturer. Improper tool sizing can cause fiber damage or cause the tool to not strip the tube from the fiber. These buffer tube sizes range from <NUM> to <NUM> and a certain tool can only be used over a small range (. <NUM>) because of the precision involved.

Current tools are highly specialized and sized specifically for the buffer tube. They have a split housing design with scoring blades on each side that penetrate the wall of the buffer tube with a side hinge to allow the tool to be placed over the tube section. These tools are specifically sized with blade depths and inside diameter. Loading a smaller or larger tube could cause damage to the fibers within the tube. Some tools combine multiple channels into one tool. This saves the end user from using multiple tools for different cables. However, this tool also causes loading errors from using the wrong channel and fiber damage from clamping the tool when the buffer tubes has spanned multiple channels.

Other tool designs use shaving as the means of exposing a window in the buffer tube. The resulting buffer tube window exposes the individual fiber strands, but it is critical that the act of opening the buffer tube window does not nick or contact the individual fiber strands. However, the current platforms do not have the accuracy to shave the buffer tube for smaller sized cables (~less than <NUM>). Other, more expensive tools use shaving to remove the buffer tube, however they are very complicated. The precision is a result of accurately machined inserts that are used for each individual buffer tube size. The tool body itself is very expensive and for each buffer tube size a precision insert must be purchased. This is not an economical or versatile solution. <CIT> describes a tube slitting tool having at least one blade extending into a passage and the side of the passage opposing the blade is curved. <CIT> discloses a cable stripper including a first body and a second body which can be moved relative to each other in a ratcheting movement or in a non-ratcheting movement in order to clamp a cable therebetween.

It would be useful to have an improved means to remove fiber optic strands from buffer tube.

Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a tool and for removing insulation in mid-span of a cable carrying a plurality of signal-transmitting conduits which utilizes an improved fiber alignment channel, fine adjustment mechanism, and range multiplying feature to maximize precision and range of the tool.

It is another object of the present invention to provide a tool and for removing insulation in mid-span of a cable carrying a plurality of signal-transmitting conduits which allows for all buffer tubes to be accurately shaved all with one tool.

It is still another object of the present invention to provide a tool having a fine adjustment barrel for accurate setting adjustment.

It is another object of the present invention to provide a tool having a cable alignment arc which orients fibers inside buffer tube and creates accurate and repeatable presentation of fiber to blade and preload area.

It is a further object of the present invention to provide an access tool which is easily manufactured from a polymer.

It is yet another object of the present invention to provide a range multiplying feature to effectively double the range of the tool.

It is still a further object of the present invention to provide an access tool having a blade which is easily replaced and is secured by blade supports which limit the flex of the blade.

It is another object of the present invention to provide a tool including cable sizing gaps for field evaluation of tool settings.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

The above and other objects are overcome by the features of the claims.

The present invention is directed to a tool for removing insulation in mid-span of a cable carrying a signal-transmitting conduit comprising a lower body section and an upper body section movable toward and away from the lower body section. The tool includes a curved mandrel disposed on the lower body section, the curved mandrel having a central peak portion and adjacent portions curving downward away from the peak portion, to present a mid-span portion of the cable insulation on a side away from the mandrel peak portion. Said curved mandrel including a cable channel disposed along a curved surface of the curved mandrel, the cable slidable along the cable channel when the cable is disposed in the cable channel. The tool includes a blade disposed on the upper body section, the blade movable toward and away from the curved mandrel. The tool includes a cable guide disposed on the upper body section wherein the cable guide secures the cable in the cable channel when the upper body section is in a position toward the lower body section. The cable is securable in said cable guide and the curved mandrel in a curved position, allowing the blade to shave the cable insulation allowing access to the signal-transmitting conduit. The tool includes an adjustment barrel having a length and a central axis extending the length of the barrel and including a plurality of height adjustment surfaces each adjustment surface disposed at a different distance from the barrel axis wherein each height adjustment surface positions the blade a different distance from the mandrel.

The tool may include an adjustment knob for controlling the distance between the upper body section and the lower body section when the tool is in a closed position.

The adjustment knob may include a knob face and a plurality of sizing notches disposed in the knob face, each sizing notch corresponding with the diameter of different diameter cables.

The blade may extend through the cable guide to contact the portion of the cable insulation at the mandrel peak portion when the upper body section is in a position towards the lower body section.

The lower body portion may include at least one alignment member and the upper body portion may include at least one alignment opening slidingly engageable with the at least one alignment member wherein the upper body portion maintains a position parallel with the lower body portion when the upper body portion is moved toward or away from the lower body section.

The tool may include a stop fastener disposed on the at least one alignment member wherein the upper body portion is limited in the distance the upper body portion is movable in a direction away from the lower body portion.

The tool may include a loading member contacting the cable insulation on the side of the cable away from the mandrel, in a location adjacent to and prior to the cable insulation being shaved by the blade, and blade supports contacting both sides of the blade over a substantial portion of the surface thereof, the tool housing being adjustably secured to the curved mandrel to adjust the distance therebetween.

The plane of the blade may be at an acute angle to the longitudinal axis of the cable at the mandrel central peak portion, and the blade may have a cutting edge oriented perpendicular to the cable longitudinal axis and cut a desired circumferential width of the insulation.

The cable insulation on the side of the cable away from the mandrel peak portion may be in tension before being contacted by the blade.

The barrel and control surfaces may be planar, and the different adjacent barrel surfaces around the barrel circumference set to increasingly greater or smaller distances from the central axis.

The tool may include a loading member contacting the cable insulation on the side of the cable away from the mandrel, in a location adjacent to and prior to the cable insulation being shaved by the blade.

Another aspect of the present invention is directed to a method for shaving insulation from a cable carrying at least one signal-transmitting conduits. The method includes the following steps,.

The figures are for illustration purposes only and are not drawn to scale. The invention itself, however, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings which describe and show a preferred embodiment of the present invention in various side, top, bottom and perspective views.

In describing the embodiment(s) of the present invention, reference will be made herein to the drawings below and <FIG> attached hereto in which like numerals refer to like features of the invention.

The present invention provides precise tool and method of use to shave an access window into a range of sizes of buffer tubes for signal-transmitting conduits, primarily fiber optic cables. The tool may also be used for shaving insulation from other cables or tubes carrying the signal-transmitting conduits such as electrical wires.

In a first embodiment of the shaving tool <NUM> shown in <FIG> and <FIG> with individual components shown in <FIG>, the shaving or mid-span access tool includes lower body portion12 is slidingly engageable with guide base member <NUM>. Lower body portion <NUM> includes a small tube channel <NUM> for the insertion of a small buffer tube. Lower body portion <NUM> includes a large tube channel <NUM> on the opposite side of the lower body portion <NUM> from the small tube channel <NUM>. Upper body member <NUM> includes a large tube guide <NUM> for securing the large buffer tube in large tube channel <NUM>. Upper body member <NUM> includes a large tube guide <NUM> for securing the large buffer tube in large tube channel <NUM>. Alignment cylinders <NUM> are disposed in cylinder openings <NUM> on lower body portion12 and slidingly engage the alignment openings <NUM> on guide base member <NUM> whereby the lower body portion <NUM> and guide base member <NUM> may move toward and away from one another. The alignment cylinders <NUM> may be secured in the cylinder openings <NUM> with fasteners (not shown) through the outer openings <NUM> (shown in <FIG>). Compression springs <NUM> disposed around the alignment cylinders <NUM> urge the guide base member <NUM> away from the lower body portion12 for biasing the tool <NUM> in an open position, allowing a buffer tube to be inserted into the small tube channel <NUM> or large tube channel <NUM>. Alignment posts <NUM>, <NUM>' extend from the lower body portion12 and upper body portion <NUM> and engage post openings <NUM> for added stability as the lower body portion12 slides toward or away from guide base member <NUM>. As seen clearly in <FIG>, small channel flange <NUM> provides further cable support for small tube channel <NUM> and large channel flange <NUM> provides further cable support for large tube channel <NUM>.

An adjustment barrel <NUM> shown in <FIG> extends through lower body portion <NUM> and is rotatingly secured to the lower body portion <NUM> by a first barrel opening <NUM> and a second barrel opening <NUM>. The adjustment barrel includes height adjustment surfaces 62a-h, each adjustment surface disposed at a different distance from the barrel axis <NUM>. A control surface <NUM> on the guide base member <NUM> is movable toward the adjustment barrel <NUM> as the shaving tool <NUM> is moved to the shaving position. The control surface <NUM> contacts one of the barrel adjustment surfaces 62a-h which is positioned parallel with the control surface. When contact is made between the control surface <NUM> and the barrel adjustment surfaces 62a-h which is positioned parallel with the control surface <NUM>, the shaving tool <NUM> is in the closed and shaving position. Rotation of the barrel <NUM> positions a different barrel adjustment surface 62a-h parallel to the control surface <NUM> so that in the closed position, the distance between the tube channel and tube guides are different in each of the adjustment barrel <NUM> positions. The tool <NUM> also has sizing gaps 68a-h on adjustment knob <NUM> and sizing gaps 69a-h on adjustment knob <NUM>, each sizing gap of different widths that operate as gauges to allow the end user to determine which barrel position should be used. In the field, it is not practical that the end user will know what diameter they are working with so the sizing gauge will help establish the tool setting. Each sizing gap may be located adjacent a numerical indicium corresponding with the buffer tube diameter. <FIG> shows the consecutive sizing gaps 69a-h with the first and smallest sizing gap 69a adjacent to the last and largest sizing gap <NUM>. Similarly, <FIG> shows the corresponding barrel adjustment surface 62a-h with the first and smallest barrel adjustment surface 62a adjacent to the last and largest barrel adjustment surface <NUM>. The first adjustment surface 62a can also be seen further from the barrel axis <NUM> than the last adjustment surface <NUM>, the first adjustment surface 62a setting the access tool <NUM> at a position for shaving the smallest cable and the last adjustment surface <NUM>, when in the active position, setting the access tool <NUM> at a position for shaving the largest cable. When using the opposite side of the access tool <NUM>, the access tool <NUM> shaves cables in the next smaller range since the distance.

<FIG> shows the portion of the upper body member <NUM> including a pair of blade supports <NUM> which supports blade <NUM> along a substantial portion of the blade length L. <FIG> show top and side views and <FIG> shows a close up of the microbevel on the blade cutting edge. The upper body member <NUM> includes a securing pin groove <NUM> which engages a securing pin <NUM> extending through the blade pin opening <NUM> when the blade <NUM> is in the installed position. The blade <NUM> includes a microbevel <NUM> having a cutting edge <NUM> at a larger angle to the blade top surface <NUM> than the relief surface <NUM>. <FIG> shows a portion of the upper body member <NUM> with the securing pin <NUM> and blade <NUM> removed. The securing pin/blade configuration make it easy to remove the blade <NUM> by sliding the securing pin <NUM> from the blade pin opening <NUM> in the direction of arrow <NUM> and sliding the blade outwardly from between the blade supports <NUM>. A blade groove <NUM> may be disposed on one side edge of the blade <NUM> to engage a corresponding protrusion (not shown) between the blade supports <NUM> to further support the blade <NUM> from sliding in the lengthwise direction.

The lower body portion <NUM> includes at least one alignment member <NUM> and the upper body portion includes at least one alignment opening <NUM> slidingly engageable with the at least one alignment member <NUM> wherein the upper body portion <NUM> maintains a position parallel with the lower body portion <NUM> when the upper body portion <NUM> is moved toward or away from the lower body section <NUM>. A stop fastener <NUM> is disposed on the at least one alignment member <NUM> wherein the upper body portion <NUM> is limited in the distance the upper body portion <NUM> is movable in a direction away from the lower body portion <NUM> and including a compression spring <NUM> disposed on the at least one alignment member <NUM> biasing the upper body portion <NUM> away from the lower body portion <NUM>.

In a method of using mid-span access tool <NUM> shown in <FIG>, a user first determines the setting to use by placing the intact buffer tube <NUM> in one of the sizing gauges 68a-h, 69a-h and if the tube will not fit in the attempted gauge, trying another sizing gauge, repeating until a snug fit is obtained. The adjustment knob <NUM>, <NUM> to which the buffer tube fits is then rotated until the indicia corresponding to the fitting gauge is positioned in the active position. The buffer tube <NUM> is then placed in the corresponding tube channel <NUM>, <NUM> and the upper body member <NUM> is urged toward lower body member <NUM> until the contact surface <NUM> contacts the barrel surface <NUM> in the active surface position. The cable is then pulled in a direction <NUM> toward the blade <NUM> wherein a portion of the cable insulation is shaved from the buffer tube. Alternately, the access tool <NUM> is pulled in direction <NUM> with respect to the stationary cable <NUM>, wherein a portion of the cable insulation is shaved from the buffer tube. The user then allows the upper body member to move away from the lower body member by releasing the pressure which maintains the tool in the closed position. The shaved cable is the removed from the access tool <NUM> and the internal cable members are accessible by the user.

In a second embodiment of the tool <NUM> shown in Figs. 1C, <FIG> include the tool top half or first housing portion 22a, tool bottom half or second housing portion 22b shown in phantom lines, adjusting barrel <NUM>, and range multiplying device <NUM>. The tool <NUM> is cost effective and easily manufactured from injection molded plastic components. Buffer tube <NUM> containing multiple optical fiber stands <NUM> is loaded into the lower tool half 22b and the upper tool half 22a is closed onto the buffer tube <NUM>. The end user pulls the tube <NUM> with respect to the tool <NUM>. The pulling action passes the insulation layer <NUM> around the outer surface of buffer tube <NUM> across the cutting edge <NUM> of the blade <NUM>. The tool sets the blade depth (as will be discussed further below) and the blade <NUM> shaves a window into the buffer tube <NUM> by removing a strip of the surrounding insulation layer <NUM>' at a precise and controlled depth of cut. The shaving continues until the end user stops pulling the buffer tube <NUM> or opens the tool by raising top half 22a.

The tool may include a loading member <NUM> contacting the cable insulation <NUM> on the side of the cable <NUM> away from the mandrel <NUM>, in a location adjacent to and prior to the cable insulation being shaved by the blade <NUM>. The tool <NUM> may include blade supports <NUM> contacting both sides of the blade <NUM> over a substantial portion of the surface thereof. The tool <NUM> may include a tool housing 22a having fixedly attached a loading member <NUM> contacting the cable insulation <NUM> on the side of the cable <NUM> away from the mandrel <NUM>, in a location adjacent to and prior to the cable insulation being shaved by the blade and blade supports <NUM> contacting both sides of the blade <NUM> over a substantial portion of the surface thereof, the tool housing 22a being adjustably secured to the curved mandrel <NUM> to adjust the distance therebetween. The plane of the blade <NUM> is at an acute angle to the longitudinal axis of the cable <NUM> at the mandrel central peak portion <NUM>, and the blade <NUM> has a cutting edge <NUM> oriented perpendicular to the cable longitudinal axis and cuts a desired circumferential width of the insulation. The signal-transmitting conduits <NUM> are optical fibers or alternately may be metal wires. The insulation on the side of the cable away from the mandrel peak <NUM> portion is in tension before being contacted by the blade <NUM>. The barrel <NUM> and control surfaces <NUM> are planar and the different adjacent barrel surfaces around the barrel circumference set to increasingly greater or smaller distances from the central axis <NUM>. Tool upper half 22a includes an upper control surface <NUM> and a variable control surface <NUM> moveable in and out of position between the selected barrel surface <NUM> and the base control surface <NUM>. The variable control surface <NUM> may be a spacer. The tool <NUM> includes a knob <NUM> for rotating the barrel <NUM>, the knob <NUM> having indicia <NUM> thereon to indicate the selected one of the barrel surfaces <NUM> presented toward the control surface <NUM>.

Each tool half also includes cable channel <NUM>. The channel includes geometric features that allow the tool <NUM> to shave or strip insulation on the large range of tube sizes. As the tool <NUM> is closed to its desired setting, the partial cable channel sections 40a and <NUM> in the upper and lower tool halves 22a, 22b, respectively, form a complete conduit for the cable to pass through.

Each setting of knob <NUM> moves the blade <NUM>, preload area <NUM> and constraint surfaces 40a in the tool top half 22a as a group. This ensures consistent position of these components. These features move relative to the datum arc of the lower channel section or mandrel 40b and adjustment surfaces <NUM> of barrel <NUM> in the tool bottom half 22b.

The blade <NUM> may be positioned in the top tool half 22a and its support <NUM> is contained in the same detail as the upper constraint surface. The blade support wall <NUM> positions blade <NUM> at acute angle α with respect to the cable or tube <NUM> axis, is integrated into the tool upper half 22a and eliminates any blade movement or flex. The blade <NUM> is accurately secured by a tight pitting guide pin <NUM>. This ensure stable, well supported blade position that is accurately located regardless of position of top half 22a with respect to bottom half 22b.

The buffer tube <NUM> is loaded onto the curved mandrel <NUM> in the tool bottom half 22b. Mandrel <NUM> has a central peak portion <NUM> and adjacent portions 44a, 44b curving smoothly downward away from the peak portion. The configuration of mandrel 40b presents for shaving a mid-span portion of the insulation <NUM> of cable tube <NUM> on the tube upper side, away from the mandrel peak portion <NUM>. The tool top half 22a then slides down to close the gap and moves until the downward-facing control surface <NUM> on the tool upper half 40a bottoms out on one of the upward-facing surfaces <NUM> of adjustment barrel <NUM>. The linear preload area <NUM> facing downward on upper half 40b contacts tube <NUM> on its upper surface near mandrel peak portion <NUM> and establishes a controlled sizing region for the loose buffer tube <NUM> as it passes to the blade <NUM> to be shaved. By forcing the buffer tube <NUM> through and along the datum arc of mandrel 40b, the tube is preloaded so that the insulation layer at the upper tube surface above mandrel peak portion <NUM> is in tension. This preloading acts to control the outer skin tension of the loose buffer tube <NUM>. It also assists in urging and/or grouping the internal fiber strands <NUM> toward the lower portion of tube <NUM>. Such preloading with the mandrel 40b datum arc, in conjunction with the linear preload area <NUM>, creates a very repeatable and accurate interaction with the blade <NUM> across a range of buffer tube <NUM> sizes.

The blade <NUM> depth settings are achieved by closing the two halves of the tool. The gap between the tool halves are set by the adjusting barrel <NUM>, which is housed in the tool bottom half 22b. Barrel <NUM> rotates about central axis <NUM> and has plurality of surfaces <NUM> around its circumference. Each barrel surface <NUM> is located at a different distance from axis <NUM>, with the radial distance increasing from one adjacent surface to the next, until the barrel rotates <NUM>° where the largest radius surface is adjacent to the smallest radius surface. The varying radial distances of the surfaces <NUM> allows different height settings for each partial turn of the barrel by knob <NUM>. The design shown uses <NUM> specific adjustment surfaces per revolution, which are identified by indicia <NUM> on the knob, but the invention is not so limited, and may have more or less than <NUM> settings or surfaces. The individual settings may correspond to <NUM>-<NUM> buffer tube sizes - typically representing <NUM> incremental sizing. End users can use this fine adjustment to accurately set the tool for optimal shaving conditions. As the settings increase though barrel rotation, the upper and lower surfaces 40a, 40b of cable channel <NUM> are spread apart. This ensures each buffer tube <NUM> undergoes the same relative blade depth, preload, and curve diameter. This setting mechanism is accurate because it acts on a control surface <NUM> of upper tool half 22a and a barrel surface <NUM> diameter feature on the other half 22b.

The range multiplying device <NUM> is a spacer or shim that may double or otherwise increase the effective cable diameter range of the tool. It provides a variable control surface <NUM> slideable on track <NUM> in and out between the barrel <NUM> and base control surface <NUM> in top half 22a of the tool by movement of control handle <NUM>. The thickness of the variable control surface <NUM> is sized to make all channel settings increase a specific distance, for example <NUM>. This shim, along with the channel geometry ensures each buffer tube is properly constrained without causing interference for other buffer tube sizes.

The tool <NUM> also has sizing gaps <NUM> of different widths that operate as gauges to allow the end user to understand which barrel position should be used. In the field, it is not practical that the end user will know what diameter they are working with and the sizing gauge will help the end user quickly establish the tool setting.

Claim 1:
A tool (<NUM>, <NUM>) for removing insulation in mid-span of a cable (<NUM>) carrying a signal-transmitting conduit (<NUM>) comprising:
a lower body section (<NUM>) and an upper body section (<NUM>) movable toward and away from the lower body section (<NUM>);
a curved mandrel (<NUM>) disposed on the lower body section (<NUM>), the curved mandrel (<NUM>) having a central peak portion (<NUM>) and adjacent portions (44a, 44b) curving downward away from the central peak portion (<NUM>), to present a mid-span portion of the cable insulation (<NUM>) on a side away from the mandrel peak portion (<NUM>), said curved mandrel (<NUM>) including a cable channel (<NUM>, <NUM>) disposed along a curved surface of the curved mandrel (<NUM>), the cable (<NUM>) slidable along the cable channel (<NUM>, <NUM>) when the cable (<NUM>) is disposed in the cable channel (<NUM>, <NUM>);
a blade (<NUM>) disposed on the upper body section (<NUM>), the blade (<NUM>) movable towards and away from the curved mandrel (<NUM>);
a cable guide (<NUM>, <NUM>) disposed on the upper body section (<NUM>) wherein the cable guide (<NUM>, <NUM>) secures the cable (<NUM>) in the cable channel (<NUM>, <NUM>) when the upper body section (<NUM>) is in a position toward the lower body section (<NUM>); and
wherein the cable (<NUM>) is securable in said cable guide (<NUM>, <NUM>) and the curved mandrel (<NUM>) in a curved position, allowing the blade (<NUM>) to shave the cable insulation (<NUM>) allowing access to the signal-transmitting conduit (<NUM>);
characterized by
an adjustment barrel (<NUM>, <NUM>) having a length and a central axis (<NUM>) extending the length of the barrel (<NUM>, <NUM>) and including a plurality of height adjustment surfaces (62a - h, <NUM>) each adjustment surface (62a - h, <NUM>) disposed at a different distance from the barrel central axis (<NUM>) wherein each height adjustment surface (62a - h, <NUM>) positions the blade (<NUM>) a different distance from the curved mandrel (<NUM>).