Abstract:
A cable-stripping tool having two parts which can rotate relative to one another about an axis and of which a first part carries a cutting blade in the vicinity of said axis and a second part of which carries a hook which can move axially and which is biased towards an end position relative to the cutting blade by means of a first spring element. A cam disc is non-rotatably connected to the first part and can be moved axially therealong. The cam disc has around its periphery mutually spaced engagement formations which are intended to co-act with a cam follower carried by the second part. A second spring element is adapted to bias the cam disc axially into contact with the cam follower. A third spring element is adapted to rotationally bias the second part relative to the first part.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a cable-stripping tool having two parts which can rotate relative to one another about an axis and of which a first part carries a cutting blade in the vicinity of the axis and a second part carries a hook which can move axially and which is biased towards an end position relative to the cutting blade by means of a first spring means. The hook has a concave side which faces towards the cutting blade and which functions to receive the cable to be stripped, and the hook also includes a generally axially oriented stem which is received in the tool. 
     U.S. Pat. No. 6,073,349 teaches a cable-stripping tool which comprises a first part and a second part that can be rotated relative to each other about an axis and of which the first part carries a cutting blade and the second part carries a hook. The hook is axially moveable and is biased towards an end position relative to the cutting blade by means of a first spring means, wherein the hook has a concave side that faces towards the cutting blade for receiving a cable to be stripped, and wherein the hook has a generally axially oriented stem which is received in the tool. 
     2. Description of the Related Art 
     In the case of the tool according to U.S. Pat. No. 6,073,349, the first part includes a handle that has a radial shoulder and that is biased by a spring peripherally in relation to the second part, so as to bias the shoulder into abutment with an attachment on the second part, wherein the attachment is displaceable axially and has two axially spaced abutment portions that lie in different circumferential positions and that can co-act with the shoulder to define respectively a first and a second position of rotation of the cutting blade relative to the hook. 
     The body also includes a further abutment, wherewith the handgrip can be twisted manually relative to the second part against the force of said spring, until the shoulder lies against said further abutment, which defines a third position of rotation. 
     The first and the second parts are returned to the first position of rotation as soon as the handgrip and the second part are released relative to each other. The positions of rotation correspond respectively to blade positions in which the blade is perpendicular to the axial direction of a cable to be stripped and received in the hook, a blade position which is inclined to the axial direction, and a blade position which is parallel with the axial direction. 
     One drawback with a tool of this known kind is that the first and second parts have mutually a rotational end position which must be maintained by continuous setting of torque manually and requiring manual procedures to be carried out in order to switch between the two remaining rotational positions. 
     A further drawback is that the body, and therewith the cutting blade, take two different positions of rotation when the tool is relieved of load. 
     Another drawback is that it is necessary to undertake comprehensive dismantling of the tool in order to change the hook. 
     Another drawback is that hook elements of mutually different effective lengths are not commercially available in respect of the tool. 
     SUMMARY OF THE INVENTION 
     One object of the invention is to provide a tool of the aforesaid kind with which the cutting blade can be set stably in pre-selected orientations relative to the body/hook, by manually twisting the handgrip relative to the body. A further object is to ensure that the blade will return to a predetermined position relative to the hook when the load on the hook is quickly relieved in an axial direction. 
     Yet a further object is to provide a tool construction that enables tool hooks to be easily exchanged, and to provide hooks of different effective lengths. 
     Still another object is to provide a tool construction in which the free end of the hook stem forms an instrument with which a hook element can be easily released from the tool. 
     These objects are achieved, either fully or partially, with a cable-stripping tool constructed in accordance with the invention. 
     According to an important feature of the invention, the tool includes a cam disc which is non-rotatably coupled to the first part and arranged for axial movement therealong. That side of the cam disc which lies proximal to the cutting blade has engagement formations disposed in spaced relationship around its periphery. A cam follower carried by the second part is able to co-act with said formations in order to set the blade in corresponding positions relative to the second part. A second spring means functions to axially bias the cam disc into contact with the cam follower at a pre-chosen force. A third spring means functions to rotatably bias the second part to a pre-selected position of rotation relative to the first part or handgrip, in which the blade may be perpendicular to a cable gripped by the hook. 
     The first part includes a hollow handgrip and a pin which is disposed centrally in the handgrip and which carries a cutting blade. The second part is a body which is rotatably mounted in the handgrip and which has a pin-receiving recess. 
     In one preferred embodiment, the hook element is adapted to be brought into contact with the cam disc, either directly or indirectly, through the medium of its spring when the hook element is released so that the cam disc will be displaced axially, at least briefly, and pass free from the cam follower. During this brief time period, the third spring means is able to twist/rotate the body and the handgrip to a predetermined, normal position. 
     The cam disc formations and the cam follower are by force and shape coupled, for instance by being rounded to enable the cam follower disc to be rotatably displaced relative to the cam follower by manually twisting the handgrip relative to the body, wherewith the second spring means functions to permit axial displacement of the cam disc on the one hand and to maintain the contact between the cam follower and the cam disc on the other hand, so as to hold the cam disc, and therewith also the cutting blade, in set positions against the action of the second spring means. 
     The stem portion of the hook is preferably received in a releasable latching arrangement on a carrier element which can be moved axially along the pin and which is secured against rotation relative to the body. The handgrip and the body have openings which, in the normal position of the cam disc relative to the body, are in alignment with each other and with a release latch in the latching device, whereby the latch can be released by inserting an instrument through the openings so as to enable the stem part of the hook to be withdrawn from the carrier element in conjunction with effecting a hook exchange. The tool includes associated exchange hooks or replacement hooks, and the free ends of respective hook stems each have the form of a pin which forms said instrument. The tool may also include a number of readily replaced hooks of mutually different effective lengths that adapt the tool to cables of mutually different diameters. The latches may be pretensioned towards latching positions, and the free stem-portion of the hook may have a wedge shape so as to move the latch away from its latching position when inserting the hook stem into the carrier element, until the latching element engages in a latching recess in the hook stem under the action of spring bias. 
     An inventive cable-stripping tool will now be described by way of example and with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic axial section view of an inventive cable-stripping tool. 
     FIG. 2 is a schematic view taken on the line II—II in FIG.  1 . 
     FIG. 3 is a schematic sectional view taken on the line III—III in FIG.  1 . 
     FIG. 4 is a schematic sectional view taken on the line IV—IV in FIG.  3 . 
     FIG. 5 is a view corresponding to the view in FIG.  2  and shows a variant of the hook-stem carrier element. 
     FIG. 6 is a schematic sectional view taken on the line VI—VI in FIG.  5 . 
     FIG. 7 is a schematic illustration of the end-part of the hook stem. 
     FIGS. 1-4 illustrate a cable-stripping tool for stripping a cable  30 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     The tool includes a generally tubular handgrip  1  that has a bottom  2  which carries a central pin  3 , an end-part  10  of which extends out of the tool and carries a cutting blade  17 . A body  7  is mounted for rotation relative to the handgrip  1  in the tubular tool. 
     The body includes an end wall  8  that has a central opening  9  through which the end-part  10  of the pin extends. In an eccentric position, the end wall  8  has an opening  16  for receiving a straight shaft or hook stem  20  whose end is connected to a carrier element  40  that can be moved axially relative to the body but that is non-rotatable in relation thereto. It will be seen that the carrier element  40  has an opening  44  through which the pin  3  extends. The element  40  includes a nose  41  that engages between two axially extending and parallel guide flanges  42  on the body  7 . 
     The hook  22  has a hook part  21  which is adapted to centre the cable  30  in relation to the cutting blade  17 . 
     A spring  50  acts axially between the end-part  10  of the pin  3  and the carrier element  40  such as to urge the cable  30  against the cutting blade  17  through the medium of the hook part  21  of the hook element  22 . 
     The bottom end-part of the pin  3  carries axial splines  4  which engage with corresponding axial splines  34  on an opening-defining wall  52  on a cam disc. The cam disc  5  can thus be moved axially along the pin  3  and is secured against rotation relative thereto as a result of the engagement between the spline formations  4 ,  34 . 
     The body  7  carries a cam follower  60  which co-acts with a peripheral region of the cam disc  5 . Mutually spaced in said peripheral region are formations  70 ′,  70 ″ in which the cam follower  60  can engage. Provided between the bottom part  2  of the handgrip and the cam disc  5  is a pressure spring  76  which biases the disc  5  into contact with the cam follower  60 . 
     Located between the handgrip and the body  7  is a spring  51  which strives to return the handgrip  1  and the body  7  towards a mutual position of rotation in which the cam follower  60  rests on the upper side of the cam disc in a position  70  which, for instance, may correspond to the blade  17  lying in a plane normal to the axial direction of the cable  30 . 
     The formation  70 ′ (rounded recess) on the cam disc can define, in co-action with the cam follower  60 , a cutting blade orientation in which the blade  17  cuts a helical slit in the cable casing as the tool (the hook  21 ) rotates about the cable axis. The third formation  70 ″ corresponds to the cutting blade  17  lying in an axial plane of the cable  30 . The cutting blade  17  can thus be set to stable positions of rotation relative to the body  7 , with the aid of the recesses  70 ′,  70 ″ and the cam follower  60 , and therewith relative to the hook  22 , against the action of the spring  51 . 
     FIG. 1 shows a downwardly and forwardly projecting cylindrical part  43  on the carrier, element  40 . 
     When the hook element  22  is released from a position in which the spring  50  is pressure-loaded, the hook and its carrier element  40  will move down into contact with the cam disc  5 , wherein the characteristic and stroke length of the spring  50  is chosen so that the for-wardly projecting part  43  of the carrier element will drive the cam disc  5  down against the action of its axial biasing spring  76 , so that the disc  5  will pass free from its engagement with the cam follower  60 . The spring  51  then returns the handgrip  1  and the body  7  to a normal position whilst the cam disc is out of contact with the cam follower. 
     It will be seen from FIG. 4 that the formations/recesses  70 ′,  70 ″ in the cam disc  5  and the cam follower  60  are rounded so that when the hook  22  is applied to a cable  30  an operator can cause the cam disc  5  to be turned so that the cam follower  60  will be received in a chosen recess  70 ′,  70 ″ by manually twisting the handgrip  1 , wherewith co-action between the cam follower and the recess establishes a lock against rotation, even against the action of the return spring  51 . Naturally, this mutual rotation between the handgrip  1  and the body  7  must allow the cam follower  60  and the cam disc  5  to move axially, which is permitted by the spring  76 . The spring  76  in combination with the curvatures of the cam follower  60  and the co-action of the recesses  70  can thus provide a retaining force against the action of the return spring  51 . Moreover, the cam follower  60  and the recesses  70  shall provide a wedging effect which results in axial displacement of the cam disc against the spring  76  in response to an applied torque. 
     It will be seen from FIG. 5 that the carrier element  40  has an axially directed recess  45  which receives the bottom end-part of the hook stem  20 . The nose part  41  of said carrier element has a radially extending channel  46  which is aligned with an opening  72  in the body  7  and an opening  11  in the handgrip  1  when the tool is in its normal state, towards which it is biased by the spring  51 . 
     It will also be seen that a spring tongue  47  affixed to the carrier element  40  carries a locking pin  48  which extends through a corresponding guide and into the channel  45  so as to be able to engage a latch opening  24  in the hook stem  20  when said stem is inserted down into the channel  45 . It will also be seen that the end of the hook stem  20  has a bevel  26  that forms a wedge surface which will function to move the locking pin  48  away as the hook stem  20  is inserted into the channel  45 . 
     It will also be seen that the end-part of the hook stem includes a narrow, elongate rod portion  27 . The rod portion  27  on the stem-end of a replacement hook  22  can be inserted through the openings  11 ,  72  and through the channel  46  so as to press the latch pin  48  to one side and out of the opening  24 , whereafter the hook element  22  of said tool can be lifted up to pass free from the latch pin  48  and the rod portion  27  of the replacement hook can then be drawn out to permit continued withdrawal of the hook element  22  of said tool. 
     The stem-part of the replacement hook can then be easily placed in position through the eccentric guide channel  16 , and down into the receiving channel  45  of the carrier element, wherewith the spring element  47  causes the carrier pin  48  to engage with the opening  24  when the stem  20  is positioned correctly in the element  40 . 
     The bottom plate  2  of said handgrip may include a container for storing replacement cutting blades  17 . 
     The hook stem may have a shoulder or ledge  28  that co-acts with the upper side  8  of the body, so as to define a hook end position. The latch mechanism for fastening the hook stem will then be exposed through the openings. 
     The spring  50  may be adapted to knock down the cam disc temporarily out of contact with the cam follower, although the spring  50  may alternatively be made stronger than the spring  76 , so that the cam disc  5  will be held depressed at a distance beneath the cam follower  60  when the tool is unloaded (no cable in the hook). The hook stem  20  may have an abutment that co-acts with the upper side of the end-wall  8  of said body  7 . 
     As a cable  30  is inserted into the hook, the hook is lifted so that the spring  50  will no longer act on the cam disc  5 , wherewith the spring  76  is able to press the cam disc  5  against the cam follower  60 . The body  7  and the handgrip  1  can now be turned manually to stable rotational positions defined by the engagement of the cam follower  60  with respective formations  70 ,  70 ′,  70 ″ on the cam disc  5 . 
     The invention being thus described, it will be apparent that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be recognized by one skilled in the art are intended to be included within the scope of the following claims.