Insulation stripping tool with striker means

An insulation stripping tool of the pliers-type includes an adjustable pull rod stop device for limiting the extent of travel of the longitudinally displaceable pull rod and the cutting and stripping blades connected thereto, thereby to produce only partial removal of a length of severed insulation layer from an insulated conductor. An adjustable conductor stop device is mounted on at least one of the cutting and stripping blade holders for limiting the extent to which the end of the insulated conductor is inserted into the open mouth of the stripping tool. A stationary scale is mounted on one of the handles adjacent the adjustable conductor stop device.

REFERENCE TO RELATED APPLICATIONS

This application is related to the co-pending applications filed by the same inventors on the inventions entitled “Insulation Stripping Tool With Displaceable Knife Carrier Means”, Ser. No. 12/290,558 filed Oct. 31, 2008, and “Hand Grip Shell for Pliers-Type tools”, Ser. No. 12/290,557 filed Oct. 31, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

An insulation stripping tool of the pliers-type includes an adjustable pull rod stop or striker device for limiting the extent of travel of the longitudinally displaceable pull rod and the cutting and stripping blades connected thereto, thereby to produce only partial removal of a length of severed insulation layer from an insulated conductor. An adjustable conductor stop device is mounted on at least one of the cutting and stripping blade holders for limiting the extent to which the end of the insulated conductor is inserted into the open mouth of the stripping tool. A stationary scale is mounted on one of the handles adjacent the adjustable conductor stop device.

2. Description of Related Art

A insulation stripping pliers are well known in the prior art, as shown by the German patent No. DE 195 12 132 C1 (U.S. Pat. No. 5,724,870). The design shown and described there has worked very well in practice. The stripping pliers is configured so that a pull rod can move in the lengthwise direction of the pliers mouth and two stripping elements are fastened to this in order to move along with it and thereby pull the layer of insulation off from a cable. On one of the stripping elements is placed a cable stop, which can move along the stripping element. The drawback to this type of stripping pliers is that the placement of the cable stop does not allow for a precise adjustment, and also the mounting of the cable stop on the stripping element by being pushed onto it is in need of improvement. A partial stripping of the severed insulation layer from the conductor is not possible in this stripping tool.

The U.S. Pat. No. 6,910,401 discloses a stripping pliers with a cutting unit that contains two pivot-mounted arms spring-loaded against each other and having cutting elements at their two ends, while the cutting unit is accommodated between clamping claws and moves along with them. Connected to this cutting unit is a pull rod and a clamping and pulling mechanism. On the lower arm, a movable single-piece cable stop is fastened. The fastening of the cable stop to the arm is by a locking tongue, which engages with a toothed groove at the side walls of the arm. With this type of fastening, there is a danger that the cable stop will get stuck or be hard to move. Again, partial stripping of the severed insulation length is not possible here.

The present invention was developed to provide a stripping pliers that is suitable for the partial stripping of cables with the most diverse thicknesses of insulation layers. Another object is to develop an improved cable stop for the stripping pliers.

SUMMARY OF THE INVENTION

Accordingly, a primary object of the invention is to provide an insulation stripping tool of the pliers-type including an adjustable pull rod stop or striker device for limiting the extent of travel of the longitudinally displaceable pull rod and the cutting and stripping blades connected thereto, thereby to produce only partial removal of a length of severed insulation layer from an insulated conductor.

A further object of the invention is to provide adjustable conductor stop means mounted on at least one of the cutting and stripping blade holders for limiting the extent to which the end of the insulated conductor is inserted into the open mouth of the stripping tool. A stationary scale is mounted on one of the handles adjacent the adjustable conductor stop device.

The stripping pliers of the invention enables an easy partial stripping of a conductor cable.

The partial stripping stop of the invention is easy to operate, economical to make, and easy to integrate in the stripping pliers. Thanks to the configuration of the partial stripping stop as an L-piece, it is easy to make and enables an easy partial stripping process. The configuration of an adjusting cam enables an even more precise adjustment for the partial stripping of the insulated conductor or cable.

The two-piece form of the conductor stop means enables a precise and easily operated mechanism.

DETAILED DESCRIPTION OF THE INVENTION

For an initial overview of the pliers-type insulation stripping tool1of the present invention, reference is first made toFIGS. 20 and 24, wherein a pair of handle members2and3are pivotally connected for pivotal movement between open and closed positions about a pivot axis49. At one end, the handle member3includes a shell portion4having a transverse end wall4aand a pair of parallel spaced side walls52that define therebetween a chamber in which are arranged a pair of pivotally connected blade holders15and16.

A clamping jaw8is pivotally connected with the shell4by means of a removable pivot pin19that extends through opposed openings21contained in the shell side walls. The clamping jaw8is provided at its free end with a durable clamping insert9arranged opposite a corresponding clamping insert10carried by the shell end wall4a. The blade holders15and16are provided at their free ends with cutting and stripping blade means12and13(FIG. 1), and with stripping means25and26, respectively. Adjustable conductor stop means14are provided on the lower blade holder for limiting the extent to which an insulated conductor is introduced longitudinally within the open mouth55of the tool. Adjustable depth control means44are provided in the cutting jaw8for controlling the relative position of the associated upper blade holder16, thereby to control the depth of cut in the insulation layer produced by the cutting and stripping blade13. Fixed scale59provided on the clamping jaw adjacent the depth control means44indicates the appropriate setting to be made in accordance with the diameter of the insulated conductor that is to be stripped. Scale S on the shell portion4indicates the extent to which the insulated conductor is to be longitudinally introduced into the mouth of the stripping tool. In the following description of the figures, terms such as above, below, left, right, front, behind, etc., refer exclusively to the sample representation and position of the pliers chosen in the respective figures. These terms are not to be understood restrictively, i.e., these relations may change in different working positions or by mirror symmetry design or the like.

FIGS. 1 and 2show a stripping pliers1with two hand levers2and3. One hand lever3is a single piece with a housing shell4, while the other hand lever2can is mounted and can swivel on the housing shell4.

A detachable grip shell5is pulled onto the hand levers2,3and can be replaced by a larger or smaller grip shell, depending on the size of the user's hand, so that the grip width of the stripping pliers can be modified.FIG. 3shows, besides one embodiment of the stripping pliers for the hand levers2and3, a replacement grip shell47for the upper hand lever3, which is adapted to the contours of the hand lever3and encloses the hand lever3on three sides. It would also be conceivable to have a molding adapted to the back of the hand lever as a grip shell replacement, or a U-shaped grip shell, which covers both the back and the side regions of the hand lever3. As another alternative, one could also consider a replacement grip shell47which can be pulled onto the first grip shell5to enlarge the grip width, so that the grip shell5covering the hand lever remains on the hand lever. Preferably, the grip shell5has at least one locking tooth6, which can engage in a lock opening7in the hand lever3to provide the grip shell5a stable and secure purchase on the hand lever3.

The pivotable hand lever2is mounted movably on the housing shell4, thanks to a mounting bolt49, which passes through boreholes50in the side walls51of the hand lever2and in the side walls of the housing shell4. Part of the side walls51of the hand lever2, especially the part around the boreholes, lies against the inner walls of the housing shell4. In this way, the hand lever2is guided in the housing shell4. The swiveling hand lever2has, at its left end, a cutting appliance with a cutting blade27, which when the hand lever is swiveled moves toward the other hand lever against a cutting blade28arranged on the housing shell4, so that a cable introduced in this spot can be cut through. The housing shell4is preferably shaped as a round mouth48in this spot for introducing a cable to be cut.

In a special embodiment shown inFIGS. 25 to 26C, a locking lever63is arranged on the housing shell4in front of the cutting appliance or the opening of the round mouth48. This locking lever is arranged on the housing4, preferably next to the cutting blade28, at its end facing the cutting appliance by means of a pivot axis64in front of the opening of the round mouth48, and thus can pivot on the housing. To secure the locking lever63to the housing4, the locking lever63is configured with a locking cam65, which sticks out from the locking lever63toward the side surface of the housing4and can lock inside a recess67on the side surface of the housing4.FIGS. 26B and 26Cshow the locking lever63in a locking position, where the round mouth48is blocked by the locking lever63. The round mouth opening48is thus blocked by the locking lever63, one end face66of the locking lever63being fixed against the opposite side of the round mouth48. Alternatively, the pivot axis64of the locking lever63can also be placed on the opposite side of the round mouth48. To prevent an unintentional separation or cutting through of an electrical cable which has accidentally gotten into the cutting appliance, the locking lever63is rotated from its neutral position close against the housing4to the opposite side of the round mouth48to block the round mouth48. This prevents a cable from being placed in the round mouth48, so that when the swiveling hand lever2is activated for a stripping maneuver the two cutting blades27,28will still be moved toward each other, but no cable can be cut through.

A clamping jaw8is mounted and can swivel on the housing shell4, thanks to a mounting bolt19, which passes through boreholes20,21in the side walls51of the clamping jaw8and in the housing shell4. Part of the side walls51of the clamping jaw8, especially the part around the boreholes20, lies against the inner walls52of the housing shell4. In this way, the clamping jaw8is guided in the housing shell4.

At the forward end wall4aof the clamping jaw4is attached a clamping jaw insert9, formed of a durable rigid material, such as steel. Opposite this clamping jaw insert9, especially its pressing piece53, is secured in the same manner another clamping jaw insert10at the tip of the housing shell piece4, forming a lip of the pliers mouth. The clamping inserts9and10consist of a sheet-like pressing piece53and a pin54standing upright on the surface, projecting into the tip of the clamping jaw8and being held there by friction or form-fitting. The clamping jaw8and the a forward end wall of the housing shell4, on the left inFIG. 1,2, together form the mouth55of the stripping pliers.

One blade holder15and16each is arranged at the bottom of the clamping jaw8and the top of the front housing piece4, behind the clamping jaw inserts9,10in the direction x of insertion of a cable. As can be seen inFIGS. 1 and 4, a stripping blade12,13projects from both blade holders15,16at their front ends. The position of the stripping blades12,13on the blade holders15,16in the cable insert direction x is chosen so that the edges of the blades meet when the pliers is operated. These stripping blades can be designed as massive blades or, as is evident fromFIG. 4, preferably as a set of lamellas56. The advantage of this configuration is a better adapting of the lamellas to the contour of a cable being stripped. Further in the mouth, on one of the blade holders15,16, preferably on both of them, is arranged an ejector25,26, which prevents insulation scraps from sticking to the stripping blades12,13. The lower ejector25is shown as an example inFIGS. 10 and 11. It is designed as a spring. Preferably, it has an S-shape, one end making contact with the piece of insulation being ejected and the other end is passed around a bolt57, on which the stripping blade12is also secured per the embodiment shown inFIG. 1.

Further into the mouth, a movable cable stop means14is mounted on the lower blade holder15, located in the housing shell4, to allow for different stripping lengths. The cable stop14, as can be seen inFIG. 5-7, is composed of a stop31, a stop lock element33and a compression spring32. The stop lock element33is guided in the stop31by slanted oblong holes34, each of which engages with a protrusion35located on the inner lengthwise sides of the stop31.

The mode of operation of the cable stop14is shown inFIG. 5-9. When the cable stop means14is activated by pressing on an operating surface38on the stop release element33, the stop release element33is pushed laterally relative to the stripping pliers against the compressive force of a compression spring32located between the stop member31and the opposite end of the stop release element33, and thanks to the guiding of the stop release element33in the stop31by the oblong holes34and protrusions35of the stop31, it is forced downwardly to disengage a tooth rack arrangement36arranged on the stop31from a corresponding tooth rack arrangement39running along the longitudinal sides of the blade holder15. The cable stop member31can then be moved longitudinally of the blade holder15. If one then lets go of the operating surface38on the stop member31, the compression spring32forces the stop lock element33upwardly toward the starting position of the stop. The stop member31will be lifted upwardly to cause re-engagement of the tooth rack arrangements36,39of stop31and blade holder15, thereby to again fasten the cable stop14on the blade holder15.

In order to support an exact adjusting of the cable stop for a desired stripping length, a scale S is applied to the housing shell4in the area of the blade holder15,16parallel with it. Preferably, the scale consists of millimeter rulings, but other units are also possible, of course. Preferably the scale is placed directly above or below the blade holder15,16on the housing shell4.

In the pliers mouth55, a compression spring17sits on the lower blade holder15, pressing against the upper blade holder16and counteracting the force exerted by the user on the pliers mouth55, and opening the pliers mouth55once again when the hand levers2,3are let go.

The blade holders15,16are removably hooked into a double-hook arrangement29a,29bat the end of a pull rod29. This double-hook arrangement has the profile of the number “3” and open toward the blade holders, whose ends engage in an opening58provided for this purpose in the end pieces of the blade holders and securely hold the blade holders in this way, so that when the pull rod moves horizontally the blade holders move along with it. In the front region, the blade holders15,16are guided by the inner sides of the front piece of the housing shell4and the inner sides of the clamping jaw.

To replace the blade holders15,16, one must first remove the pivot pin19, securing the clamping jaw8, from the bearing position46and the clamping jaw8from the housing shell, as shown inFIG. 20-23. Then one swings the upper blade holder16upward to take it out from the upper fork of the pliers mouth. Once the upper blade holder16has been removed, the lower blade holder15lying in the housing shell can be easily swung upward and taken out of the lower fork of the pull rod mouth. The blade holders can then be replaced by new ones or the same ones with a different blade shape.

The pull rod29runs essentially horizontally through the inside of the stripping pliers. It is mounted so that it can move horizontally. At its end pointing toward the pliers mouth is found the already mentioned mouth in the double-hook profile of an open numeral “3”, in which the blade holders are pivotally hooked to the pull rod.

In one embodiment of the stripping pliers, a partial stripping stop means30is fastened in the hand lever3behind the end of the pull rod away from the blade holders (15,16). A detail view of the partial stripping stop means30is shown inFIGS. 12-14. This allows for a partial stripping62of an insulated piece of wire61. It is preferably configured as an L-shaped piece130that is pivotable about pivot axis131and includes arms130aand130bof different lengths. The mounting of the partial stripping stop means30is situated in the junction between the arms of the L-bend, so that the partial stripping stop means30can be optionally adjusted so that the pull rod29is limited in its backward movement by the longer leg130bof the L-piece130, and thus a full stripping of the wire piece is prevented. In the other adjustment possibility shown, the partial stripping stop130is rotated away from the path of the pull rod29so that the latter can move freely.

In another embodiment shown inFIGS. 15-17, the freedom of movement of the pull rod29is limited by an adjusting cam40. This adjusting cam40is mounted and can pivot above the hand lever2at the right next to the operating lever18, which also controls the movement of the pull rod29. In the partial stripping position shown inFIG. 16, the adjusting wheel40limits the operating lever18such that the pull rod29and thus also the blade holders15,16execute only a limited travel. The adjustment for full stripping is shown inFIG. 17. Here, the adjusting wheel is fixed by a cam strip41present underneath the adjusting wheel and faces away from the operating lever, so that it has more freedom of motion and thus the pull lever29and the blade holders15,16can travel the full distance.

In another embodiment shown inFIGS. 27 and 28, the freedom of movement of the pull rod29is limited by a partial stripping stop means30′ fashioned as a leaf spring. As can be seen in the detail view of this partial stripping stop30′ inFIG. 28, this is likewise freely secured in the hand lever. The leaf spring30′ is freely secured in the hand lever by a rear end, facing the end of the pliers. The front end of the leaf spring points in the direction of an end71of the pull rod, which is pushed through an opening in a stop70, which is arranged in the hand lever3. Preferably, the rear segment of the pull rod is grasped by a spring element69, which counteracts a stripping movement of the pull rod in the direction of the end of the pliers in that the one end of the spring element69rests against the stop70and with its other end it is compressed by the movement of the pull rod in the direction of the stop. In this way, when the pliers is squeezed, after traveling a distance X the pull rod29hits the partial stripping stop1, which indicates that the partial stripping process is finished. In order to perform a full stripping, the pull rod29has to be forced further against the leaf spring30, so that it is deflected.

According to a further embodiment, the freedom of movement of the pull rod29is limited by a partial stripping stop30″ which, as shown inFIGS. 29 to 31, is fastened and can rotate by a pivot axis73in the hand lever3. Furthermore, the partial stripping stop30″ has a housing75, in which a dampening element72is mounted, which sticks out from the housing at one end face74and impinges on the pull rod29as it is pushed backward during a partial stripping process.

In another embodiment shown inFIGS. 32 and 33, the pull rod29has a recess79, in which a bolt78spring-loaded in a housing76engages. The housing76is secured by a pin77to the housing4of the stripping pliers. In this way, by pressing the bolt78into the recess79the freedom of movement of the pull rod29in the direction of the lengthwise axis of the pull rod is limited to the length of the recess79. This ensures that the electrical cable is only partly stripped, that is, the insulation is cut through, but the piece of insulation remains on the cable.

As can be seen inFIGS. 1 and 18, an adjusting slide24for changing the height of the blade holder is arranged above the blade holder16in the clamping jaw8. As shown inFIG. 19, this slides on a slide plate23. The adjusting slide24has on either side a flexible leg43with corrugated outer contact surfaces44at the ends, which stick out through openings45in the side surfaces of the clamping jaw8and can be pressed in by the user in order to move the adjusting slide along the lengthwise axis of the clamping jaw. The adjusting slide24is flat in its front region and increases in thickness toward the rear. The flexible legs of the adjusting slide merge at the front end with the main body of the adjusting slide and spread away from it toward the other end. The main body of the adjusting slide24tapers in its width backward in the region of the legs, to allow the legs to be pressed against the main body. The rear region of the adjusting slide24has the same width as the slide plate23located underneath, only the end piece being somewhat more narrow. If one moves the adjusting slide24forward, i.e., to the left in the figure, the slide plate and thus also the blade holder16resting against it will be forced downward. This enables a fine tuning of the cutting depth for the wire being stripped, so that one can also make precision cuts in the insulation layers of cables with insulation layers of different diameter. To indicate the direction in which the adjusting slide needs to be moved for an insulation layer with a given diameter, a scale59and several ring symbols60of progressively larger radius are placed on the clamping jaw8, preferably on the back of the clamping jaw8.

When using the stripping pliers, as the two hand levers2,3are squeezed together by one hand, the hand lever2is forced in the direction of hand lever3. The clamping jaw8is at first forced downward against the housing shell4by a lever mechanism including the operating lever18pivotally connected at one end18awith the handle member2(FIG. 15) and carrying at it other end a roller18bthat engages a corresponding cam surface8b(FIG. 20) on the clamping jaw8. This clamps down on a piece of cable11placed in the pliers. At the same time, the stripping blades12,13of the blade holders15,16cut into the jacket of the piece of cable12. If one continues to squeeze the pliers, the pull rod and the blade holders15and16pivotally connected thereto will be pulled backward by the lever mechanism, thus pulling the severed insulation layer of the conductor backward from the bare conductor wire. Depending on the position of the partial stripping stop30, the insulation will be entirely or only partly pulled off from the piece of cable. The ejector spring26will be placed under tension. As soon as the user lets go of the pliers handle members2and3and removes the insulated conductor or cable from the pliers, the clamping jaw8will be pushed back into the open position by the compression spring17, and the ejector spring will relax and discharge the stripped piece of insulation from the mouth of the pliers.

While in accordance with the provisions of the Patent Statutes the preferred forms and embodiments of the invention have been illustrated and described, it will be apparent to those skilled in the art that changes may be made without deviating from the invention described above.