US3838489A

US3838489A - Hand operable compressing tools

Info

Publication number: US3838489A
Application number: US00374677A
Authority: US
Inventors: E Pepper
Original assignee: Post Office
Current assignee: Post Office
Priority date: 1972-07-06
Filing date: 1973-06-28
Publication date: 1974-10-01
Anticipated expiration: 1991-10-01
Also published as: GB1397134A; BE818051A; AU5745973A; DE2334292A1; DE2334292B2

Abstract

A manually-operable tool for electrically and mechanically coupling a plurality of electrical conductors whcih are placed in a compressible connector, the connector being placed in a cavity in the tool housing to be compressed by a ram. The ram is moved by means of a rotatable cam which may be so shaped and mounted as to give a range of magnitudes of movement of the ram to compress connectors of varying thickness or to give a reproducible magnitude of movement to compress connectors all of the same thickness. The tool includes a jig having a supporting foot and a seat for the tool operator, the tool housing, the seat and the supporting foot being so arranged that the tool housing and the supporting foot are independently vertically adjustable relative to the seat being horizontally movable relative to the seat and foot combination. BACKGROUND OF THE INVENTION This invention relates to manually operable tools for compressing small articles, such as connectors for joining electrical conductors, and is particularly useful for compressing connectors of the tubular type, generally closed at one end. One such tubular type of connector is the so-called B-wire connector which comprises a plastics sheath encasing a brass shell and a phosphor-bronze metal lining having wire engaging means including tangs projecting inwardly of the lining. Wires to be joined have their end portions inserted into the sheath which is then compressed to make an electrical and mechanical connection. It is imperative that the correct pressure be applied to the connector since insufficient pressure will not enable the tangs to pierce the insulation of the wires or grip the wires, while too much pressure will crush the wires and destroy the gripping and piercing action of the tangs. Hand tools are known for compressing electrical connectors of the B-wire type between a set of jaws having a conventional crossed levers construction and action. To produce the desired pressure on the connector sheath with this type of tool it is necessary for the operator to apply appreciable force to the tool handles. This large force requirement and the weight of the hand tool produces operator fatigue after very few compressing operations. In addition, though this type of tool is often fitted with a pawl device to ensure application of a compressive force greater than a predetermined minimum force, the position of the jaws in applying such predetermined minimum force is usually appreciably different from the position of the jaws when applying a predetermined maximum force for the tool thus giving rise to non-reproducability of compressive forces. When jointing conductors such as telephone cables laid in ducts in the ground, a variety of conditions may be faced by the jointer. For example, if conductors lead into a jointing box, the jointer will be required to crouch at the edge of the box while effecting jointing operations. Alternatively, if conductors lead into a manhole, the jointer must descend into the stand in the manhole while making the joints. Both of these operations can result in appreciable discomfort to the jointer should he be required to maintain his position for any length of time. The present invention enables the design of a tool to meet the following objectives: TO ACHIEVE REPRODUCIBILITY OF COMPRESSIVE FORCES WHEN CRIMPING CONNECTORS OF A STANDARD THICKNESS; TO ACHIEVE COMPRESSIVE FORCES OF DESIRED MAGNITUDE WHEN CRIMPING CONNECTORS OF DIFFERENT THICKNESSES; TO REDUCE FATIGUE EXPERIENCED BY JOINTERS WHEN JOINTING MULTICONDUCTOR CABLES; AND TO PROVIDE A TOOL AT WHICH AN OPERATOR CAN WORK COMFORTABLY AND WITHOUT HAVING TO ADOPT AN AWKWARD POSTURE. According to the invention there is provided a manually operable tool for electrically and mechanically coupling a plurality of electrical conductors with the aid of compressible connector, said tool comprising a housing containing a slidable ram and rotatable cam formed with lobes adapted to engage the ram as the cam is rotated to drive the ram to compress said connector between a thrust face of said ram and a reaction face of a connector receiving cavity in said housing. In one embodiment of the invention the lobes have apices distant from the centre of rotation of the cam by mutually unequal amounts; for example, the cam has a regular polygonal profile and is mounted off-centre. Thus for one chosen orientation of the dam, a predetermined angular rotation thereof drives the ram through a predetermined travel to provide the desired compression of a thick connector. For another chosen orientation of the cam, a predetermined angular rotation thereof drives the ram through an increased travel to provide the desired compression of a thin connector. In an alternative embodiment of the invention the cam profile is a regular polygon, for example, a triangle, and the cam is mounted at its geometric centre. Preferably the cam is unidirectionally rotatable; this could be achieved, for example, by a pawl and ratchet mechanism, the pawl being mounted on the cam and the co-operating ratchet being mounted on the housing. Preferably the tool includes a jig comprising a seat, a supporting foot and three interlockable intermovable members, wherein movement of a first of the members relative to the other members alters the vertical disposition of said seat relative to the housing, movement of a second of the members relative to the other members alters the vertical disposition of said seat relative to said supporting foot, and movement of a third of the members relative to the other members alters the horizontal disposition of said supporting foot and said housing relative to said seat.

Description

United States Patent Pepper Oct. 1, 1974 HAND OPERABLE COMPRESSING TOOLS Primary Examiner-Thomas H. Eager [75] Inventor: Edwin Henry Charles Pepper, g g' or F'rm Kem0n Palmer &

Dageham, England Sta r00 [73] Assignee: The Post Office, London, England 7 ABSTRACT [22] Filed: June 28, 1973 A manually-operable tool for electrically and mechanically coupling a plurality of electrical conductors [21] Appl' 374677 whcih are placed in a compressible connector, the connector being placed in a cavity in the tool housing [30] Foreign Application Priority Data to be compressed by a ram. The ram is moved by July 6, 1972 Great Britain 31746/72 means of a rotatable Cam which y be SO Shaped and mounted as to give a range of magnitudes of move- [52 U.S. cl. 29/203 H mm of the ram to compress connectors of varying [51] Int. Cl. H0lt '43/04 thickness or to give a reproducible magnitude of [58] Field of Search 29/203 H, 203 J, 200 B, movement to Compress connectors of the Same 29 203 DT, 203 D, 203 HT thickness. The tool includes a jig having a supporting foot and a seat for the tool operator, the tool housing, [56] References Cit d the seat and the supporting foot being so arranged that UNITED STATES PATENTS the tool housing and the supporting foot are independently vertically adjustable relative to the seat being 3,143,790 8/1964 Over et al. 29/203 H horizontally movable relative to the seat and foot combination.

8 Claims, 5 Drawing Figures saw 1 or 5 PATENTED BUT I 1974 HAND OPERABLE COMPRESSING TOOLS BACKGROUND OF THE INVENTION This invention relates to manually operable tools for compressing small articles, such as connectors for joining electrical conductors, and is particularly useful for compressing connectors of the tubular type, generally closed at one end.

One such tubular type of connector is the so-called B-wire connector which comprises a plastics sheath encasing a brass shell and a phosphor-bronze metal lining having wire engaging means including tangs projecting inwardly of the lining. Wires to be joined have their end portions inserted into the sheath which is then compressed to make an electrical and mechanical connection. It is imperative that the correct pressure be applied to the connector since insufficient pressure will not enable the tangs to pierce the insulation of the wires or grip the wires, while too much pressure will crush the wires and destroy the gripping and piercing action of the tangs.

Hand tools are known for compressing electrical connectors of the B-wire type between a set of jaws having a conventional crossed levers construction and action. To produce the desired pressure on the connector sheath with this type of tool it is necessary for the operator to apply appreciable force to the tool handles. This large force requirement and the weight of the hand tool produces operator fatigue after very few compressing operations. In addition, though this type of tool is often fitted with a pawl device to ensure application of a compressive force greater than a predetermined minimum force, the position of the jaws in applying such predetermined minimum force is usually appreciably different from the position of the jaws when applying a predetermined maximum force for the tool thus giving rise to non-reproducability of compressive forces.

When jointing conductors such as telephone cables laid in ducts in the ground, a variety of conditions may be faced by the jointer. For example, if conductors lead into a jointing box, the jointer will be required to crouch at the edge of the box while effecting jointing operations. Alternatively, if conductors lead into a manhole, the jointer must descend into the stand in the manhole while making the joints. Both of these operations can result in appreciable discomfort to the jointer should he be required to maintain his position for any length of time.

The present invention enables the design of a tool to meet the following objectives:

to achieve reproducibility of compressive forces when crimping connectors of a standard thickness;

to achieve compressive forces of desired magnitude when crimping connectors of different thicknesses;

to reduce fatigue experienced by jointers when jointing multiconductor cables; and

to provide a tool at which an operator can work comfortably and without having to adopt an awkward posture.

According to the invention there is provided a manually operable tool for electrically and mechanically coupling a plurality of electrical conductors with the aid of compressible connector, said tool comprising a housing containing a slidable ram and rotatable cam formed with lobes adapted to engage the ram as the cam is rotated to drive the ram to compress said connector between a thrust face of said ram and a reaction face of a connector receiving cavity in said housing.

In one embodiment of the invention the lobes have apices distant from the centre of rotation of the cam by mutually unequal amounts; for example, the cam has a regular polygonal profile and is mounted off-centre. Thus for one chosen orientation of the dam, a predetermined angular rotation thereof drives the ram through a predetermined travel to provide the desired compression of a thick connector. For another chosen orientation of the cam, a predetermined angular rotation thereof drives the ram through an increased travel to provide the desired compression of a thin connector.

In an alternative embodiment of the invention the cam profile is a regular polygon, for example, a triangle, and the cam is mounted at its geometric centre.

Preferably the cam is unidirectionally rotatable; this could be achieved, for example, by a pawl and ratchet mechanism, the pawl being mounted on the cam and the co-operating ratchet being mounted on the housmg.

Preferably the tool includes a jig comprising a seat, a supporting foot and three interlockable intermovable members, wherein movement of a first of the members relative to the other members alters the vertical disposition of said seat relative to the housing, movement of a second of the members relative to the other members alters the vertical disposition of said seat relative to said supporting foot, and movement of a third of the members relative to the other members alters the horizontal disposition of said supporting foot and said housing relative to said seat.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a compressing tool and jig according to the invention;

FIG. 2 is a view from one side of part of the compressing tool of FIG. 1 with a retaining washer removed;

FIG. 3 is a sectional view along the line III III of FIG. 2 showing the retaining washer in position;

FIG. 4 is a sectional view of the tool head preparatory to a compressing operation and taken along the line IVIV; of FIG. 3; and

FIG. 5 is a sectional view similar to FIG. 4 but shown at a different stage of a compressing operation DESCRIPTION OF PREFERRED EMBODIMENT Referring firstly to FIG. 1, there is shown a handoperable jig-mounted compressing or crimping tool. The jig comprises a seat 1 of foamed polyurethene composition which is suitably dimensioned to be disposed at the edge of a joint box with rear faces of a pair of feet 2 adjacent the side of the joint box. Alternatively the seat 1 can be placed on a support (not shown) of suitable height and shape. A pair of legs 3 integral with the seat 1 ensure that the seat is spaced from the supporting surface.

A spacing rod 4 is supported from the undersurface of seat 1 by a'bracket 5 fixed to the seat. The spacing rod may be slid longitudinally away from or towards the seat 1 in order to alter the relative disposition of the seat 1 and a crimping head 6. The rod 4 may be clamped in position by a clamp 7 associated with bracket 5.

The distal end of spacing rod 4 has a bore extending therethrough, in which bore is fixedly located a rod 8 which supports the crimping head 6. A portion of rod 8 is located within a hollow cylindrical member 9, which member is integrally attached to a hollow support column 10. The rod is slidable within cylindrical member 9 so as to alter the relative disposition of the seat assembly to the support column 10, which disposition may be fixed by a clamp 11 associated with member 9. An angle-iron cross-member 12 is fixed to support column to provide a foot rest for the tool operator. An extendible foot member 13 is slidable within the lower portion of support column 10 to ensure that the jig rests on the floor of the joint box. The footmember 13 may be clamped in position by a clamp 14.

Extending perpendicularly from rod 8 and integrally fixed thereto in a bracket (not shown). A support member 15 pivotable in a horizontal plane has one end hinged to the bracket. The other end of support member 15 is attached to the lower surface of a tray in which connectors (not shown) are stored until required for a crimping operation.

The upper end of rod 8 supports a generally inverted U-shaped member 16 whose front end is integral with a plate 17. A pair of flanges 18 extending forwardly of the plate 17 provide a bay 19 into which a cable (not shown) having conductors therein to be connected may be placed. The cable is heid in position by a length of flexible cord 20 having one end (not shown) suitably clamped to the head. To clamp and cable in position the card 20 is led around the edges of flanges 18 to pressthe cable into bay 19 and is then fed through a cut-out 21 in plate 17 to a channel-shaped internally ridged plastics moulding 22 in which the other end of card 20 is held in a friction fit.

Rigidly mounted on U-shaped mounting member 16 is the compressing tool head 6. To joint a pair of wires, the wires, the wires are firstly inserted into the open end of a B-wire connector (not shown) and the connector is deposited, with its sealed end downwards, into a slot 23 in the crimping head. Compression of a connector is obtained by pivotal movement of a lever 24 from position A to position 8 (FIG. 2). The movement of the lever 24 is governed by stops 61 projecting from the crimping tool head 6, which stops prevent a further compressing operation from occurring prior to the lever 24 being returned to position A. The return motion of lever 24 is aided by a return spring 25 connecting the pivotted end of the lever to the crimping head and located in a recess 26 in an annular disc 27 integral with the lever end.

The annular disc 27 has a generally radially extending recess 28 cut partially through its lateral thickness. A pawl 29 of generally trapezoidal section is mounted for limited pivotal movement about a peg 30 upstanding from the floor of the recess 28. Extending outwardly of a wall of the recess 28 is a cylindrical bore, in which is mounted a compression spring 31 which bears on the larger parallel face 32 of the trapezoidal section pawl 29..On rotation of the annular disc 27, as shown by the arrow in FIG. 2, a part of pawl face 32 successively engages cooperating faces 33 of a series of three grooves 34 formed in the end portion of a rotatable shaft 35', which grooves taper away from the end of the shaft. On rotation of the annular disc 27 in the reverse direction, the other faces of the generally V- section grooves 34 on contacting the pawl 29 cause rocking thereof to a position wherein the spring 31 is compressed. With the pawl 29 in this position, sliding motion of the end face of the pawl relative to lands 36 between the grooves 34 occurs and, accordingly, the shaft 35 is unidirectionally rotatable. The pawl and ratchet mechanism ensures that a particular compressing operation must be completed, with the desired compressive force applied, before the connector and wires (not shown) can be removed.

The shaft 35 is located in a cylindrical bore 37 in a ram housing 38, (FIG. 3). The shaft 35 has an end portion 39 of greater diameter than the diameter of bore 37 located externally of the ram housing 38 with an annular surface thereof bearing on an outer surface of the ram housing. The distal end 40 of the shaft 35 has a threaded bore 41 extending longitudinally into the shaft for engagement by a set screw 42 to clamp a retaining washer 43 for securing the shaft 35 in the ram housing 38.

Referring now also to FIGS. 4 and 5, flats 44 are formed along a central portion of shaft 35 to provide a generally triangular section cam 45 havingcurved lobes 46 formed at the vertices of the triangle. On unidirectional rotation of the shaft 35, the lobes 46 bear successively against an inner surface 47 of an inverted U-section ram 48. The ram 48 is spring biassed by a compression spring 49 located in a longitudinal recess 50 in the top surface of the ram. One end of the spring 49 is permanently in compressive engagement with a peg 51 projecting from a lower surface of a top plate 52 of ram housing 38. The other end of the spring 49 acts against an end wall 53 of the recess 56 thereby forcing the ram 48 to the left as seen in FIGS. 4 and 5, and so ensuring that surface 47 contacts the lobes 46 of the triangular section cam 45. Rotary motion of the cam in the direction of the arrow in FIG. 4 causes movement of the ram 48 to the position shown in FIG. 5, thereby compressing a connector (not shown) located between a surface 54 of a back plate 55 and the leading surface 56 of the ram 48. Surface 56 is inclined relative to back plate surface 54 so that operation of the tool compresses a uniformly sectioned connector more at its lower end than at its upper end.

This feature is desirable to attain a gradually increasing gripping force along the length of the connector and to lessen any risk of subsequent fracture of the jointed wires at the upper end of the connector.

The dimensions of the triangular cam 45 are such that the distances of the centre of rotation of the cam 45 from the mid-points of the curved lobes 46 and the cam faces 43, respectively, must differ by a distance equal to the reduction in spacing of the ram 48 from the back plate 55 required for the correct compressive force to be applied to a connector. Further rotation of the cam by means of lever 24 causes the ram to ride back under the action of spring 49 to the left as shown in FIG. 4 until the position is reached in which the ram abuts another face 43 of the cam.

A shown in FIGS. 4 and 5, a bore 57 through the base I r What is claimed is: g l. A manually operable tool for electricaly and mechanically coupling a plurality of electrical conductors with the aid of a compressible connector, said tool comprising a housing containing a slidable ram and-a rotatable cam formed with lobes adapted to engage the ram as the cam is rotated to drive the ram to compress said connector between a thrust face of said ram and a reaction face of a connector receiving cavity in said housing.

2. A manually operable tool as claimed in claim 1, wherein said lobes have apices distant from the centre of rotation of the cam by mutually unequal amounts so that for a predetermined angular rotation of the cam, the ram is driven through a distance dependent on the orientation of the cam.

3. A manually operable tool as claimed in claim 1 wherein the profile of said cam is a regular polygon in which apices of said polygon constitute said lobes.

4. A manually operable tool as claimed in claim 3 wherein the centre of rotation of the cam coincides with the geometric centre of the polygon.

5. A manually operable tool as claimed in claim 1, wherein the cam forms part of a shaft which is rotatable 6 in said housing and wherein a pawl and ratchet mechanism co-operating with the shaft and the housing ensures that the shaft and cam are unidirectionally rotatable.

6. A manually operable tool as claimed in claim 1, said tool including a jig comprising a seat, a supporting foot and three interlockable intermoveable members, wherein movement of a first of the members relative to the other members alters the vertical disposition of said seat relative to said housing, movement of a second of the members relative to the other members alters the vertical disposition of said seat relative to said supporting foot, and movement of a third of the members relative to the other members alters the horizontal disposition of said supporting foot and said housing relative to said seat.

7 A manually operable r061 as claimed in claim 3 wherein said regular polygon is a triangle.

8. A manually operable moi aeezirdi'n taaanfi cam is unidirectionally rotatable.

Claims

1. A manually operable tool for electricaly and mechanically coupling a plurality of electrical conductors with the aid of a compressible connector, said tool comprising a housing containing a slidable ram and a rotatable cam formed with lobes adapted to engage the ram as the cam is rotated to drive the ram to compress said connector between a thrust face of said ram and a reaction face of a connector receiving cavity in said housing.

5. A manually operable tool as claimed in claim 1, wherein the cam forms part of a shaft which is rotatable in said housing and wherein a pawl and ratchet mechanism co-operating with the shaft and the housing ensures that the shaft and cam are unidirectionally rotatable.

7. A manually operable tool as claimed in claim 3 wherein said regular polygon is a triangle.

8. A manually operable tool according to claim 1 wherein the cam is provided with means whereby the cam is unidirectionally rotatable.