GB2330108A

GB2330108A - Wire stripping or crimping tool with cam adjuster

Info

Publication number: GB2330108A
Application number: GB9822214A
Authority: GB
Inventors: Zdzislaw Bieganski
Original assignee: Z B TOOLS Ltd
Current assignee: Z B TOOLS Ltd
Priority date: 1997-10-10
Filing date: 1998-10-12
Publication date: 1999-04-14
Also published as: GB9822214D0

Abstract

A wire stripping or crimping tool (fig 2) has two handles 13,24 which are movable towards each other to effect a first operation to close a pair of jaws 10,17 in order to clamp a work piece. Further movement of the handles effects a second operation of either stripping a wire held between the jaws or crimping a work piece held between the jaws. In order to accommodate different sized workpieces the point at which the second operation commences is adjustable by means of a cam 60 located on a lever 8 and positioned to engage one 51 of a number of link members 50,51,52 (for the wire stripper) which serve to effect the two stage operation. A further cam member (C2 fig 4) may be located adjacent one of the jaws to adjust the initial separation of two cutting jaws (102,103 fig 4) in order to facilitate the accommodation of different sized wires.

Description

HAND TOOLS This invention relates to hand tools more particularly but not exclusively of a kind comprising two handles which can be closed together in order to operate a mechanism for performing a 2-stage operation on a workpiece. Such tools are hereinafter referred to as "of the kind specified".

The handles may be pivoted together, for example, in a scissor type linkage or there may be one relatively fixed member forming one handle, with a second handle pivoted to that, possibly via a complex linkage.

One example of such a hand tool is a wire stripper, in which one stage of the 2-stage operation is to close gripping jaws on to the exterior of a wire workpiece to thereby cause inner cutting jaws of the tool to penetrate sheathing of the wire; the second stage is to displace the cutting jaws along the axis of the wire with the cut sheath and relative to the core of the wire so as to strip the cut portion of the sheath from the wire.

Another example of such a hand tool is a terminal or female crimping tool in which jaws are closed onto the terminal to crimp the terminal or ferrule onto a wire located in the terminal during a first stage of the 2-stage operation and the jaws are released from the terminal/ferrule during a second stage of said operation. The terminallferrrrle and wire comprise the workpiece.

In each of the aforementioned examples, the total movement of the handle or handles in a complete stroke may be notionally divisible into two parts corresponding to the stages of the 2-stage operation, and the division takes place at a different point in the cycle according to the diameter (or thickness) of the work piece within a range which is acceptable in the tool.

Hence, in the case of the aforementioned crimping tool, and with a small diameter ferrule, a small or lesser portion of the lever movement is used to crimp and a larger portion is relatively idle; were it not so, the ferrule might be over-crimped and damaged, for example the ferrule may be split. In the case of the wire stripping too], the applied force may shift to cause the relativc movement along the wire once the necessary degree of gripping and cutting is effected.

It is believed the design of such hand tools has not been optimised and that it should be possible to extend the range and sizes of workpiece that can be operated by the hand tool as aforementioned.

It is an object of the present invention to provide a hand tool which is improved in at least some respect or to facilitate selective adjustment of the division point in the 2-stage operation or to provide a tool having the possible range of workpiece sizes extended.

According to the present invention there is provided a tool of a kind having two handles which can be moved relative to one another in order to operate a mechanism for performing a 2-srage operation on a workpiece, and having at least one lever, the tool comprising a cam mounted on said at least one lever, said cam being arranged for angular movement about an axis parallel with a pivot axis of that lever, and effective to vary a division point in the 2-stage operation caused by lever movement.

The cam may be a snail cam or it may be substantially circular but eccentrically pivoted.

Further according to the present invention there is provided in a wire stripping tool having two handles movable relative to one another to bring gripping jaws together to grip onto insulation on a piece of wire in a first stage of a two stage operation, and having a toggle linkage to activate means to move cutting surfaces of the tool to strip insulation from said piece of wire in a second stage of said two stage operation, a cam adjuster for adjusting the division point between the first and second stages of the two stage operation.

Still further according to the present invention there is provided in a crimping tool having two handles movable relative to one another to bring crimping jaws together to apply pressure to a workpiece in a first stage of a two stage operation, and the two handles being movable relative to one another in a second stage of the operation to release the jaws from the workpiece, an adjuster for adjusting or pre-setting the distance between the jaws prior to commencement of the two-stage operation.

Many advantageous features of the present invention will be apparent from the following description and drawings.

Embodiments of hand tools in accordance with the present invention will be described, by way of example only, with reference to the simplified, diagrammatic accompanying drawings, in which: FIGURE 1 is a part-sectional cut away elevation of a wire stripper; FIGURE 2 is a cut away elevation of a crimping tool and a reverse-side derail view of a cam with lever handle; FIGURE 3 is a perspective view drawn to a larger scale, showing crimping dies used in tool of FIGURE 2.

FIGURE 4 shows a production version of a second embodiment of a wire stripper and a detail perspective view of a cam adjuster.

Referring to FIGURE 1 of the drawings, a hand tool comprises a member 13 forming one handle and extending to a first outer gripping jaw 10 at the opposite end to the handle portion Outer gripping jaw 17 has an extension part pivoted on pin 15 journalled in the member 13, said jaw 17 being remote from the pivot pin 15.

A lever 8 is pivoted on pin 16 also carried by the member 13, and handle 24 is pivoted on pin 9 which is carried by the member 13. For convenience, the member 13 may be extended by a pair of side plates 19 fixed together and to the member 13 by screws 11 and carrying the pins 9, 16.

Rear handle 24 is provided with a cam portion 7 abutting the lever 8 so that when the handle 24 is pivoted in the direction of the arrow A, the lever 8 is moved likewise. Spring means, as described hereinafter, is provided for returning the parts to the position as illustrated in FIGURE 1.

The outer gripping jaws 10, 17 embrace inner cutting jaws 26 pivoted on pin 27 in carrier 28. A small compression spring 35 is positioned between the cutting jaws 26 in order to maintain them in contact with the inner faces adjacent the actual gripping jaws 10,17.

The carrier 27 is coupled to a slidable rod 40 by pin 39, and the rod is guided in a transverse bore in the pin 15 and in a fork 42, with a small pin 43 in the fork being captivated and running in slot 44 in the rod 40. A compression spring 70 is captivated between the fork and another abutment (not shown) on rod 40.

A three link toggle 50, 51, 52 is arranged in between the two plates 19 and has first link 50 pinned to the lever 8 at 55; a second link 51 pinned to said extension part of the outer jaw 17 at 56, and a third link 52 pinned to the rod 40 at 57.

Operation of the wire stripping tool as described is as follows: A wire workpiece (not shown) is inserted between the gripping jaws 10, 17 extending towards the pin 27 (possibly as far as a stop - not shown) and then the handle 24 is pivoted in the direction of the arrow A towards handle 13, so that the outer and inner jaws 10, 17 are closed onto the wire. An insulation sheath or external surface of the wire is gripped by the jaws ]0, 17; said sheath or external surface is to be cut and penetrated by cutting surfaces C provided at free ends of the inner cutting jaws 26. The gripping and cutting operation is effected by the link 50 performing a near straight line movement whilst the links 51, 52 act as a conventional two-link toggle and points 56, 57 separate thereby swinging the moving jaw 17 about pin 15 to cause the jaws 10, 17 to close together. Further movement of the jaws 10, 17 towards one another is not possible because of the resistance afforded by the wire. The links 50, 52 act as a conventional 2-link toggle and the closing movement provided by the handle 24 in the direction of arrow A takes the pivot points 55, 57 towards one another, thereby once again increasing the distance between the points 56, 57 but without any relative movement of the point 56. This causes the rod 40 to be axially displaced with compression of the spring 70 and that moves the inner jaws 26 relative to the outer jaws 10, 17 in the direction which will strip the cut portion of the sheath or external surface along the core of the wire.

Although the initial closing movement of the jaws 10, 17 is accompanied by near to straight line movement of the link 50, there is in fact an element of angular movement of the link 50 about its axis and there is also movement of the ]ever 8 in a direction towards the member 13 which reduces the illustrated clearance between the link 51 and the lever S..

The aforedescribed features of the hand tool and method of operation are generally known per se but, in accordance with this embodiment of the present invention, snail cam 60 is pivoted on pin 62, which pin is parallel to the pins 9 16, 15, for example, and the cam has a generally radially projecting operating lever handle 64. As illustrated in FIGURE 1, the snail cam 60 has a relatively small clearance with the link 51. If the cam 60 is turned clockwise by means of the lever handle 64 about its pivot 62, said clearance with link 51 increases.

When there is only a small clearance between the cam 60 and link 51, as illustrated, movement of the lever handle 24 brings about the stripping operation, that is to say the cutting jaws 26 are moved relative to the gripping jaws 10, 17 along the axis of the wire (or cable) and this happens before there has been much movement of the jaws 10, 17 towards one another. This feature renders the tool particularly suitable for stripping large diameter wiresicables. When the cam 60 is turned so as to create the maximum clearance between Lhe cam and the link 51, a greater degree of movement of the lever handle 24 is possible, that is to say a greater degree of closing of the jaws 10, 17 together, before the stripping operation (second stage of the 2stage wire stripping operation) commences. This is due to the pivoting action of the link 51 about pivot point 56 in an anti-clockwise direction being limited by contact with the snail cam 60.

In practice, it is found that, not only does the provision of the snail carn 60 affect the division point in the 2-stage operation cycle when closing of jaws 10, 17 ceases and stripping action commences, but, more importantly, the provision of the snail cam enables a given tool to be used effectively on a rnuch wider range of wire or cable diameters.

It will be appreciated that, within the spirit of the present invention instead of providing a handle 24 pivoted on the pin 9 with the cam 7, the lever 8 could simply be extended to perform the same function.

It is also to be appreciated that a three-link toggle is not necessarily essential to the present invention and the eccentric adjuster (cam) could be used to like effect in quite different mechanisms or hand tools.

The cam 61 may be mounted on lever S in such manner that lever handle 64 projects through an opening (usually of rectangular shape) restricting the angular movement of the lever handle between two set positions and thus restricting the angular movement of cam 60.

FIGURES 2 and 3 show a crimping tool of a type which is in generally well known in the art, comprising a pair of crimping jaws 100, 102 one of which is normally fixed, and the other of which is slidably mounted in an cncircling frame 104. The jaws 100, 102 have interdigitated web-like portions so that as one jaw 100 slides towards the other 102, the webs on one jaw 100 pass between those on the other jaw 102. This jaw design is more particularly described in prior Patent specification No.1,532,160. Usually, the jaw 100 is fixed in position, and jaw 102 is displaceable by lever mechanism 106 acting via a spring such as a stack of Belleville spring washers 108. Washers 108 have the effect enabling the pressure applied to be adjusted via the lever 106 and to a workpiece captivated between the jaws, in the position e.g. indicated by the reference 110. The arrangement is such that the lever 106 must complete a stroke before the jaws 100, 102 separate and release the crimped (e.g.) ferrulefterminal (not shown), by means of a ratchet device.

The jaws 100, 102 as described are adapted to crimp a ferrule or terminal to a square cross-section. In the conventional and well known tool, the range of sizes which can be accommodated may be of the order of 0.5 4rum2. The tool may be pre-set to a particular dimension in this range by means of a screw and nut 112 device accessible by removal of a side plate fixed to the frame 104 (the side plate is shown cut away in FIGURE 2 for clarity). Nut 112 can be rotated to pre-set the distance between jaw 102 and the springs 108, in a manner which should be selfexplanatory from FIGURE 2.

In order to provide for larger workpieces, and according to the present invention, the normally fixed jaw 100 is, advantageously, mounted for a limited degree of sliding towards and away from the other jaw 102, and an eccentric (cam) adjuster 114 is operable on appropriate rotation by a lever handle to displace the normally fixed jaw 100 to a second position more remote from the sliding jaw. FIGURE 2 shows the eccentric adjuster 1 14 in this remote position.

It has been found experimentally that use of the eccentric adjuster on the normally fixed jaw 100 can increase the range of sizes of workpieces useable with the crimping tool up to e.g. 10mm2. The adjuster 114 per se may be generally of the same fonn as in the wire stripper of FIGURE 1, that is a snail cam or an eccentrically mounted circular part, preferably with a serrated exterior engaging against the jaw, so as to ensure that the cam is not unintentionally turned from the selected position. Advantageously, by the present invention the crimping tool can be used to better effect without overcrimping on certain sizes of workpiece. Jaw 100 may be movable by 60 thousands of an inch. The adjuster 114 may, alternatively, be arranged to be normally inaccessible so that it is pre-set by the manufacturer according to a user's requirements.

FIGURE 4 shows a production version of wire stripping tool now provided with two cam mechanism C and C2. Cam C, has a lever handle L, angularly rotatable between fixed positions in order to advance or retract a slideable pin P which is able to act directly on toggle link t, in such a manner to vary a division point between the two stage operation provided by the wire stripper. In addition to this point being varied by cam Cl the second cam C2 has its own hand lever L, rotatable between fixed limits, said cam 2 being positioned on a gripping jaw 100 in such a manner that rotation thereof affects the position of cutting jaw 101 mounted on the gripping jaw 100. Cutting surfaces 102, 103 are provided on the cutting jaws 101, 104 respectively.

Thus, the production version of the wire stripping tool effectively has the advantages of both the cam action provided in the wire stripping tool shown in FIGURE 1 and the cam action of the crimping tool shown in FIGURES 2 and 3.

It is believed that the design of easily operable cams C1 and C2 by means of the lever handles L, and L2 facilitates use of the tool with a much wider range of wire (workpiece diameters) and the levers L1 and L2 operate in an incremented fashion so that there is no slip without positive movement of the lever handle IF ; the outside surface of the barrel cam C, C2 being serrated, splined or knurled.

Still further, with a wire stripping tool of this kind (and of the type as shown in FIGURE 1) the correct application of pressure on the workpiece in between gripping jaws 101. 108 for a particular size of workpiece before the wire stripping action occurs is important. Thus, by the provision of cam C, in accordance with the present invention a workpiece is not gripped to such an extent that it is nearly crushed before the stripping stage of the operation commences as could occur with tools in accordance with the prior art.

The cam adjuster C (and C2 to a lesser extent) allows a more correct gripping pressure to be set for the gripping jaws 100, 108 for a particular size of workpiece (including sizes at the extreme end of the extended range) prior to the stripping action being performed. The more the toggle links are in line the higher the transfer of force. As should be evidence from FIGURE 4, the more pin P is advanced towards toggle t, the lower gipping force is applied (for the same size of workpiece) by the gripping jaws 100, 108 prior to the stripping stage of the operation. If the user sets the wire stripping tool to a position in which the wire is gripped and cut, and the tool is ready for commencement of the stripping stage but the user believes a greater gripping pressure is necessary, cam C, could be moved to vary the division point in the two-stage operation to allow a greater gripping pressure of the jaws prior to the stripping action. Similarly, if it appears that a wire is being gripped too hard and the stripping stage of the operation is not set to commence, cam C, can be adjusted so that the stripping stage can commence. Thus, the user of the tool has much more control over the action of the tool by varying said division point in the two-stage operation to suit.

The remaining operation of the production tool shown in FIGURE 4 for stripping wire should be evident when a comparison is made with the arrangement as shown in FIGURE 1 save for the fact that an additional notch N is provided in lever handle 105 adjacent a cutting blade 106 (moveable with slidable rod 107) in order to severe a wire other workpiece (not shown) placed in the notch, simultaneously as the wire placed between the gripping jaws 100 and 108 is stripped.

It is to be understood that the scope of the present invention is not to be unduly limited by the particular choice of terminology and that a specific term may be replaced by any equivalent or generic term.

Further, it is to be understood that individual features, method or functions relating to the hand tool might be individually patentable. In particular, any disclosure in this specification of a range for a variable or parameter shall be taken to include a disclosure of any selectable or derivable sub-range within that range and shall be taken to include a disclosure of any value for the variable or parameter arranged within or at an end of the range.

The disclosure of any particular dimension in millimetres shall be taken to include the disclosure of that dimension + 5 or lOmm2. The singular may include the plural or vice versa. The tool could be arranged such that the handles of the tool are moveable away from one another to effect the twostage operation, rather than being closed towards one another.

Therefore, further according to the invention there is provided a hand tool having two handles movable relative to one another in order to operate a mechanism for performing a two-stage operation on a workpiecc, the tool being provided with two adjustable cams for varying the division point in the two-stage operation. One cam may be provided on a lever of the tool and the other may be provided on or adjacent to a gripping jaw.

Further according to the present invention there is provided a tool having any feature or combination of features derivable from the description and drawings.

Further according to the present invention there is provided a hand tool having one or more of the following features a) two cam adjusters b) a cam adjuster having a lever handle c) a cam adjuster operable without the aid of a tool (e.g. screwdriver) d) a gripping jaw with a cam adjuster e) a lever with cam adjuster f) a cam adjuster rotatable about an axis parallel with the pivotable axis of a lever on which it is mounted.

Further according to the present invention there is provided apparatus for performing a two-stage operation on a workpiece, said apparatus comprising two handles which may be moved relative to one another to effect the two-stage operation, the range of movement during the first stage of the operation relative to the range of movement during the second stage of the operation being pre-selectable in a variable or selectable manner prior to operation on a workpiece.

The term "cam" may or may not be intended to include a screw thread.

Claims

CLAIMS:- 1. A hand tool of a kind having two handles which can be moved relative to one another in order to operate a mechanism for performing a 2-stage operation on a workpiece, and having at least one lever, the tool comprising a cam mounted on said at least one lever, said cam being arranged for angular movement about an axis parallel with a pivot axis of that lever, and effective to vary a division point in the 2-stage operation caused by lever movement.
2. A tool as claimed in claim 1 in which the cam is a snail cam and/or in which the handles can be closed towards one another to operate said mechanism for performing the two-stage operation.
3. A tool as claimed in claim 1 in which the cam is substantially circular but eccentrically pivoted.
4. A tool as claimed in any one of the preceding claims in which the cam has a (generally radially) projecting lever.
5. A tool as claimed in any one of the preceding claims which is a wire stripping tool.
6. A tool as claimed in any one of the preceding claims having a toggle linkage.
7 A tool as claimed in claim 6 in which said toggle linkage is a three link toggle.
8. A tool as claimed in claim 6 or claim 7 in which the cam can be turned to increase or decrease clearance between a link of the toggle linkage connected to one of two gripping jaws of the tool.
9. A tool as claimed in claim 8 in which, with a decreased clearance, movement of the handles together brings about a stripping operation earlier than with an increased clearance, by moving two cutting jaws relative to the gripping jaws, in use, along an axis of a cable workpiece.
10. A tool as claimed in any one of the preceding claims having a second cam adjuster in one of, or on one of the, gripping jaws of the tool.
11. A tool as claimed in any one of claims 1 to 4 which is a crimping tool.
12. A tool as claimed in claim 11 having two jaws, one of said jaws being movable relative to the other to crimp a female on the workpiece said other jaw being mounted for a limited degree of sliding towards and away from the other jaw, said cam being usable to displace said other jaw to a second position more remote from the sliding jaw.
13. A tool as claimed in claim 11 or claim 12 in which a range of size of workpiece that can be accommodated varies from 0.5rum2 to greater than 4mm2 and preferably up to 10mm2.
14. A tool as claimed in any one of claims 1 ] to 13 in which the cam has a serrated exterior engaging against the jaw.
15. A tool as claimed in any one of claims 11 to 14 in which the cam is normally inaccessible to the user.
16. A tool substantially as herein described with reference to FIGURE 1 or FIGURES 2 and 3, or 4 of the accompanying drawings.
17. A tool as claimed in claim 1 having a cam substantially as herein described with reference to FIGURE 1 or 4 of the accompanying drawings.
18. A tool of the kind referred to comprising a cam mounted on the lever or on one of the levers, arranged for angular movement about an axis parallel with the pivot axis of that lever, and effective to vary the said division point in the complete cycle of operations caused by the lever movement.
19. In a wire stripping tool having two handles movable relative to one another to bring gripping jaws together to grip onto insulation on a piece of wire in a first stage of a two stage operation, and having a toggle linkage to activate means to move cutting surfaces of the tool to strip insulation from said piece of wire in a second stage of said two stage operation, a cam adjuster for adjusting the division point between the first and second stages of the two stage operation.
20. In a crimping tool having two handles movable relative to one another to bring crimping jaws together to apply pressure to a workpiece in a first stage of a two stage operation, and the two handles being movable relative to one another in a second stage of the operation to release the jaws from the workpiece, an adjuster for adjusting or pre-setting the distance between the jaws prior to commencement of the twostage operation.
21. A hand tool having two handles movable relative to one another in order to operate a mechanism for performing a two-stage operation on a workpiece, the tool being provided with two adjustable cams for varying the division point in the two-stage operation.
22. A tool as claimed in claim 21 in which one cam is provided on a lever of the tool and the other is provided on a gripping jaw.