DEVICE FOR TWISTING WIRES
DESCRIPTION The invention concerns a device for twisting together end areas of a number of wires, the device comprising a rotatable twister module which includes an axial cavity for receiving, via an inlet opening, the wire areas to be twisted together. Such a device is known from US5379809, disclosing a wire twisting device arranged to join bare end portions of a plurality of insulated electrical wires together. The known wire twisting device comprises a handle and a wire twisting member which includes a central cavity having a plurality of protrusions extending inwardly toward the central axis. The protrusions form a plurality of wire receiving peripheral channels between adjacent protrusions. The bare wire end portions to be twisted can be placed in those channels. Then the wire twisting device is rotated by hand and
simultaneously moved in longitudinal direction, causing that the bare wire end portions are twisted together. Subsequently a hollow wire connector or nut can be screwed over the twisted wire ends. The disclosed device has as disadvantage that the inward protrusions and intermediate (open) channels extend through the whole operational part of the cavity (i.e. the cavity except a bevelled guiding inlet portion) , forming long peripheral channels into which the bare wire areas are inserted before twisting. Such a shape may work in manually operated tools but is not suitable when working at higher rotation speeds, i.e. when the device should be driven electrically. The reason is that the known manual wire
twister (i.e. its twister head) must, due to its elongated protrusions/channels throughout the greatest (i.e.
operational) portion of its cavity, be moved in longitudinal
(axial) direction during its twisting action in order to release the bare wire ends from the elongated channels enclosing them. In addition, due to said longitudinal/axial motion of the wires in and through the channels, undesired friction and deformation (e.g. drifting, jamming) forces will occur, which obstruct proper and efficient operation when the known twister head would be used in a device driven by e.g. a
(high speed) electric motor.
Another hand driven wire twister tool is disclosed in
US2007215233, which tool includes a body portion having a cavity that includes a plurality of contiguous openings to receive a plurality of wires, where one area is able to receive four wires and another area to receive two wires. The tool also includes a gripping portion for gripping the tool. The body portion holds the plurality of wires in a fixed position relative to one another. Rotation of the gripping portion rotates the body portion thereby twisting the
plurality of wires together. The gripping portion may be a rod that can be inserted substantially perpendicularly into the body portion. The same disadvantages apply as mentioned w.r.t. the aforesaid US5379809, viz. -in short- no smooth and efficient operation -requested when used by professional electricians- when driven by e.g. a (high speed) electric motor . Yet another hand driven wire twister tool is disclosed in
US7662158, disclosing a screw or nut driver having a handle, a driver shaft, and a driver head for engagement with a normal or Phillips screw or a nut. An opening bore extends
into the rear end of the handle, receiving a socket having a bore provided with one or two traction pins extending
radially inwardly. Due to the fact that the traction pin(s) is/are located "halfway" the relevant bore(s), this
configuration is not fit for twisting wires at high rotation speed occurring when such twisting device would be driven by an electromotor.
One aim of this invention is to provide a twisting device which is fit to be applied by professionals, needing high work speeds, e.g. during the installation of large electrical installations .
Another aim is to provide a device which is very effective and manageable when driven by an electromotor, due to a minimal motion of the device in longitudinal/axial direction during the twisting action and minimal undesired friction and deformation effects between the wires reciprocally and between the wires and the twister head.
Yet another aim is to provide a device which includes, additional to the twister module, a stripper module which is effective to strip the wire insulation (or any other layer covering the wire) over a predetermined length which is optimally tailored to the dimensions of both the twisting module and the wire connector which is to be screwed over the twisted bare wire end areas.
According to the invention a device is provided for twisting together end areas of a number of wires, the device
comprising a rotatable twister module which includes an axial cavity for receiving, via an inlet opening, the wire areas to be twisted together, wherein the cavity includes an
operational area having a mainly parallel (e.g. circular cylindrical or hexagonal cylindrical) or slightly conical, elongated shape, which is provided with a wire twisting area which includes only one eccentric twister cam (or pin) , which extends over only a fraction (e.g. less than 50% or 30%) of the axial length of the operational area, and which is located right at the bottom of the cavity.
Preferably, the eccentric twister cam has transverse
dimensions allowing the end parts of all of the wire areas to be twisted together to be accommodated in the remaining space of the (e.g.) cylindrical cavity portion partly occupied by the twister cam. The space left, in the twisting part, by the twister cam is suitable to receive the wires to be twisted, and the twister cam is suitable to engage and to drive the end parts of said end areas of the wires to be twisted.
It is noted here that in this application the notion "cam" should be understood as any projection, protrusion, boss etc. in any suitable shape and extending, in the wire twisting area at the bottom side of the cavity, from the bottom and/or from the side wall of the wire twisting area of the cavity.
So, instead of a plurality of elongated protrusions forming a plurality of elongated wire receiving peripheral channels (see US5379809) or plurality of contiguous openings (see US2007215233 ) , as in the known prior art devices, the
operative portion of the cavity only comprises one, inwardly protruding twister cam having minimal axial dimensions (e.g. protruding inwardly only some millimetres and having a height to the bottom of the cavity of only some millimetres) , which are just sufficient to exert a rotational force to only (or
mainly) the extreme parts of the wire areas to be twisted together when the twister module is rotated around its axis.
It is noted that, alternatively, two or more of such small- sized twister cams could be provided in the axial cavity.
However, in practice, the application of only one sole small sized twister cam will give excellent results in most cases.
Due to the minimal axial dimensions of the twister cam the motions in longitudinal direction of the device during the twisting process are minimized, causing that when the twister module is energized by an (internal or external) electric motor, the twisting process is substantially sped up, contributing to a considerable increase in efficiency and decrease of labour costs, especially in large installing projects .
The device according to the invention only comprises one single axial cavity (or channel) and (preferably) one single twister cam (or protrusion) instead of -as in the prior art devices- a plurality of cavities, openings, channels,
protrusions etc. for keeping the wires in a fixed position relative to one another. Instead of keeping the wires in a fixed position relative to one another like in the prior art's configurations, the invention's "1-channel/l-cam" configuration provides that all wires are held together within one (common) twisting channel, and are rotationally actuated by one sole drive cam/protrusion. As a result of this novel configuration in which the wires are held together in one common twisting room, the wires, during the twisting process have sufficient room to be twisted together easily, smoothly and quickly into a compactly twisted set of wires, which manifests itself in particular in combination with a
(high speed) rotation motor. Further, the prior art's
configurations need longer (stripped) wire ends, which have to be shortened by cutting them off after the twisting process .
Summarizing, advantages of the configuration according to the invention include:
- easy insertion of the wires into the operational area of the cavity of the twisting module;
- less damage of the (copper) wire, easy and smooth
twisting and high quality twisted wire connections;
- less resistance of the wire packet during twisting;
- wires don't need to be shortened after being twisted. The device, comprising the twisting module, may include its own internal electric drive motor. However, the device may also mainly be constituted by the twisting module (without an integrated drive motor) , where the twisting module then is used in the same way as the well-known screwdriver-bits: in that case the twisting device is constituted by (only) the twisting module and may be provided with -like a screwdriver- bit- a connection rod (e.g. having a hexagonal cross- section) . The twisting module will be tailored to be used in
combination with (regular) wire connectors which are adapted to receive a number of wires having a mainly cylindrical or slightly conical outer shape after being twisted together. Although all kind of wires can be twisted by means of the twister device according to the invention, the device is in particular suitable for twisting non-insulated or stripped (i.e. having removed insulation) end areas of a number of
electric wires, e.g. in order to facilitate a wire connector to be clamped and/or screwed around those twisted areas.
Preferably, the twisting device includes, as a synergetically and ergonomically attractive addition to the twister module, a stripper module, arranged for stripping the end areas of wires surrounded by a cover or coating layer, e.g. insulated electric wires, over a predetermined stripping length before subsequently twisting those stripped wire areas by inserting them into the twister module and rotating it around its axis. The predetermined stripping length thus can optimally be tailored to the axial dimensions of the cavity and the twister cam. Besides, the electrician only has one tool, with which he can strip the wires and then twist them in one smoothly combined action.
The stripper module may have a configuration e.g. derived from GB1033614, disclosing a cable-stripping device which has a pair of notched jaws which are so pivoted that, as a cable held between them is withdrawn, the jaws are forced
increasingly together to shear the insulation in their vicinity .
The combined twister/stripper device thus may comprise a stripper module including an insert member arranged for receiving a predetermined end area of at least one wire to be stripped, as well as at least two spring-loaded opposite cutting blades comprising cutting edges shaped to incise, in a cutting position, at least a substantial part of the layer surrounding the wire, the cutting blades being mounted to allow them to hinge around their outer ends between the cutting position, in which the blades are forced by their spring load to rest in one common plane while their movable
inner ends are pinched together, and a wire insertion position, in which the at least one wire to be stripped pushes, opposing the spring load, the inner cutting blade ends away from each other, thus passing the cutting edges. The insert member, preferably, comprises a stop part for stopping the at least one wire inserted, via the movable inner cutting blade ends pushed away, the stop part being arranged that its stopping surface is located at a distance to the cutting edges in the wire insertion position of the cutting blades, which corresponds to the predetermined stripping length.
Hereinafter the invention will be elucidated with reference to some figures.
Figure 1 shows a first exemplary embodiment of the
device according to the invention in side view;
Figure 2 shows a second exemplary embodiment of the
device according to the invention in three views;
Figures 3a-d show the twister module, inclusive some
embodiments of the twister cam, in cross- sectional view;
Figures 4a-d show, in cross-sectional view, the operation of the twister operation of three wires having stripped end areas;
Figures 5a-c show, in cross-sectional view, an exemplary
embodiment of the stripper module in three
subsequent stages during a wire stripping
Figure 6 shows three stripped electrical wires
subsequently twisted together, provided with the clamping coil of an ordinary wire connector and provided with a complete wire connector, including its insulated housing. Figure 7 shows, in cross-sectional view, an additional module, arranged for screwing wire connector to a couple of twisted wires;
Figure 8 shows, in view, an embodiment of a stripper
module having cutting blades which are arranged for cutting two different wire diameters;
Figure 9 shows, in cross-sectional view, the embodiment of a twister module shown in figure 3a,
however, comprising an axial cavity having a slightly conical shape;
Figure 10 shows an embodiment to be used as a "twister- bit" together with an external drive;
Figures lla-b show two embodiments of the twister cam.
Figure 1 shows a first exemplary embodiment of the device comprising a housing 1 which accommodates a stripper module 2 and a twister module 3. The latter can be driven by an electromotor 4 which can be switched on and off by a switch 5 and is energized by a rechargeable battery pack 6 in a way
which is common for other battery operated tools like
electric screwdrivers, drilling machines etc.
Figure 2 shows a second exemplary embodiment of the device according to the invention in three views (in American projection) , wherein the device has a pistol like shape as often used for similar tools like electric screwdrivers, drilling machines etc., wherein the housing 1 includes a protruding hand grip la. The embodiment shown in figure 2 has similar components 1 - 6 as the embodiment shown in figure 1. The switch 5 is mounted in the hand grip la.
Figures 3a-d show three embodiments of the cavity and twister cam of the twister module 3 in cross-sectional view.
Figure 3a shows the rotatable twister module 3, connected to the electric motor 4 via a drive shaft 7 and fixed thereon by means of a socket screw 8, includes an axial cavity 9, arranged for receiving, via a guiding (e.g. bevelled or rounded) inlet opening 10, wire areas 11 of wires 12 to be twisted together. Except the guiding portion 10, the cavity 9 has a mainly cylindrical shape and is provided with an eccentric twister cam 13 extending from the bottom side 9a of the cavity 9, over only a fraction of the axial length of the cylindrical cavity portion and having transverse, i.e.
inwardly directed dimensions allowing the end parts, i.e. the extremities 14 of all of the wire areas 11 to be twisted together to be accommodated in the remaining space 15 of the cylindrical cavity portion 9 partly occupied by the twister cam 13. The twister cam 13 thus has axial and radial
(transverse, inward) dimensions which are fit to exert a rotational force to the end parts 14 of the wire areas 11 to be twisted together when the wire areas 11 are inserted into
the cavity 9, stopped by the cavity bottom 9a, and the twister module 3 is rotated around its axis, driven by the electromotor 4, via the drive shaft 7. Figures 3b - 3d show cross-sectional views of the cavities 9 and twister cams 13 of different twister modules 3, arranged for twisting different numbers of wires, e.g. three and four standard (e.g. 2.5 square millimetres) electric installation wires and for five thinner (e.g. 1.5 square millimetres) installation wires respectively. The devices shown in figures 1 and 2 are arranged that various different twister modules 3, i.e. for different possible wire combination can be mounted in the device, i.e. on the drive shaft 7 by means of the socket screw 8.
The twister cam 13 is provided with a guiding surface 16 at the side of the inlet opening 10 of the cavity 9, arranged to guide the end parts 14 of the wire areas 11 to be received in the remaining space 15 of the cavity 9 partly occupied by the twister cam 13.
Twisting of previously stripped end areas 11 of a number of electric wires 12, in order to facilitate a wire connector 17 to be clamped or screwed around those twisted areas is shown in figures 4a-d showing, in cross-sectional view, the
operation of the twister operation of three wires 12 having stripped end areas 11. The wire end areas 11 are moved
(figures 4a - b) by hand (of the operator) into the cavity 9 of the twister module 3 until their extremities 14 are stopped by the bottom 9a of the cavity 9 and they are located beside the twister cam 13, in the space left over by the twister cam 13. After that the operator holds the wires 12 and energizes the electromotor 4 by means of switch 5,
causing the twister module 3 to rotate a number of turns and applying a rotational force to the extreme parts 14 of the stripped wire areas 11, (figures 4b - c) due to which the wire areas 11 are twisted together. After the wire areas 11 are twisted together, the twisted wire areas 11 will be thrown back by the rotating twister cam 13 over only a short distance, corresponding to the (restricted) axial dimensions of the twister cam. After the twisting action the operator is able to retract (see arrow to the left in figure 4c) the twisted wires out of the twister module taking a wire
connector 17 (figure 4d) and screwing the wire connector 17 around the wire areas 11 twisted together. The wire connector 17 usually includes a housing 18 and a clamping coil 19 made of steel, mounted in the housing. After the wire connector 17 has been screwed on the wire areas 11, the wires 12 are firmly and electrically safely connected to each other, while the bare wire areas 11 twisted together are covered by the insulated housing of the wire connector 17. It is clear that the length of the bare wire areas 11 should be located inside the area which is covered by the insulated housing 18 of the wire connector 17, as more stripped wires interconnected by means of wire connectors 17 may be housed in a common junction box, where the various electrical wire junctions (interconnections) need to be insulated from each other. So it is important that the stripped and twisted areas of each junction are not too long, endangering their mutual electrical insulation, and are not too short, endangering their mutual contacting quality as too short bare wire areas may cause that the mutual contact pressure is low or
indefinite. It is thus important that the length of the stripped areas 11 is correct. On the other hand,
electricians, involved with building electrical installations
have to make large numbers of wire junctions, especially in large buildings, plants etc., while mostly being under pressure to make those junction within installation times which have to be as short as possible for normal economic reasons.
To meet that aim, the device shown in figures 1 and 2
includes a stripper module 2 the dimensions of which are tailored to the dimensions of the twister module 3 and to the dimensions of the wire connectors to be used. As an example, it is supposed in the exemplary embodiments revealed and discussed here, that the stripped and twisted area needs to be about 15 millimetres to be well suitable to be clamped and covered by commonly used wire connectors 17. The exact dimensions of the cavity 19, the twister cam 13 etc. are to be determined after practical experimentation and
engineering, e.g. keeping in mind that the axial dimension of the wire areas 11 may decrease during twisting, which effect e.g. could be compensated by using somewhat longer bare wire areas 11, e.g. having a length of 16 millimetres instead. The length reduction of the stripped area may also be dependent of the cross-section (e.g. 1.5 or 2.5 mm2) and number of wires twisted together. So it may be needed that the cavity length for a twister module 3 for e.g. five wires (see figure 3d) has to be somewhat larger than the cavity length of a twister module for three wires (see figure 3a) . In all cases, however, the stripping length 11 and the cavity and twister cam dimensions are tailored to each other and to the optimal and/or prescribed operational length of the insulated wire connector 17.
Figure 5a-c shows, in cross-sectional view, an exemplary embodiment of the stripper module 2, incorporated in the
devices shown in figures 1 and 2, shown in three subsequent stages during a wire stripping operation. The stripper module 2 thus is arranged for stripping the end areas 11 of wires 12 surrounded by a cover or coating layer, in particular
insulated electric wires, over a predetermined stripping length (e.g. 15 - 20 millimetres) before subsequently
twisting those stripped wire areas by inserting them into the twister module and rotating it around its axis. As discussed in the preceding, the predetermined stripping length is tailored to the dimensions of the cavity and the twister cam of the twister module to be used.
The stripper module 2, which can be in threaded connection to the housing 1 of the relevant device shown in figures 1 or 2, comprises an insert member 20 which is arranged for receiving a predetermined end area of a wire 12 to be stripped. Two spring-loaded opposite cutting blades 21 are provided, each comprising cutting edges 22, formed by means of concavely slanted areas 23, shown in front view in figure 5b. The cutting blades 21 rest on two shoulder parts 28 of the insert member frame 27 to allow them to hinge around their outer ends between a rest position shown in figures 5a and 5d and an inward position shown in figure 5c.
The wire 12 can be inserted, as shown in figures 5a and 5c, through an inlet opening 24 in a cover plate 25 and via the movable inner ends of the cutting blades 21, which are pushed away under the insertion force of the wire, applied by the operator (not shown) of the device, against the force of two compression springs 26 which are provided between the insert member frame 27 and the movable cutting blades 21. The insert member 20 comprises a stop part 29 for stopping the wire 12
at a distance to the cutting edges 22 of the cutting blades 21 in the inserted position of the wire 12 which corresponds to the predetermined stripping length, e.g. 15 - 20
millimetres, as discussed in the foregoing.
The cutting edges 22 are shaped to incise, in a cutting position (figure 5d) , at least a substantial part of the insulation layer surrounding the wire 12 when the operator retracts (see arrow to the left) the wire 12 out of the stripper module 2. When the wire 12 is retracted out of the stripper module 2 the movable inner ends of the cutting blades 21 are pinched together, forced to the drag force exerted by the device operator and the pivoting movement of the cutting blades 21 around the shoulder parts 28, towards their position in which they take their rest position in a common plane surface lying against the back side of the cover plate 25. Due to the incision of the insulation layer of the wire 12, the end area 11 is stripped by pulling the wire 12 out of the stripper module 2. The remaining insulation sheath 30 may be ejected into a bin 31 via a suitable slot 32 provided in the insert member 20.
Figure 6 shows three stripped electrical wires 12
subsequently twisted together, provided with the clamping coil 19 of an ordinary wire connector 17 and provided with a complete wire connector, including its insulated housing (normally the complete wire connector 17 will be screwed around the twisted bare wire areas 11) . In this way a device for stripping and subsequently twisting the stripped end areas of a number of electric wires is provided, in order to facilitate a wire connector to be clamped or screwed around those stripped and twisted areas,
the wire connector being provided with an insulation housing arranged to cover the wire connector and the stripped end areas of the electric wires, wherein the predetermined stripping length and the axial dimension of the cavity and axial dimensions of the twister cam of the twister module, is tailored to the axial dimensions of the insulation housing of the wire connector. Using this novel device will improve the economic efficiency and the technical reliability of large electrical installation projects.
The use of the device is not only restricted to electrical wires, but is also applicable in other technical areas where wires are stripped and twisted together. The device is also applicable where bare, i.e. uncovered wire is used and must twisted together for any reason.
This novel device contributes to safe and reliable
(installation) work, saving time and money and resulting less (electrical) faults. Besides, the device contributes to the health of its users, e.g. by preventing RSI and/or other muscle related complaints. Moreover, cutting off the twisted wire bundles is not needed any more, as the bare wire ends 11 are stripped at exactly the right length a twisted together then, resulting in a bundle of twisted bare wire ends which have exactly the right length to be covered by the wire connector 17. The twister cam 13 preferably is rounded off at all its edges, thus preventing break of the (copper) wires due to damage caused by the twister cam 13. Preferably, the twister module 3 is connected to its
rotational drive means, i.e. the electromotor 4 and its driving axis 7, via a coupling which is arranged for quick and easy attachment and detachment of the twister module to
and from its drive means, thus allowing quick and easy exchange of twister modules. Such couplings are generally known and may be used instead of the socket screw 8. It may optionally be preferred to provide the device with means for, during operation, detecting the rotation time and/or the number of turns made by the twister module and outputting a signal after a predetermined rotation time and/or number of turns respectively. Alternatively, the driving means of the twister module could, by installing suitable electronic control circuitry in the device, be stopped or decoupled after a predetermined rotation time and/or number of turns respectively. Besides, illumination means could be incorporated in de device, for illuminating the wires to be processed by the device and/or their
Figure 7 shows an exemplary example of a screwing module 31 which is arranged for screwing a wire connector 17 to a couple of twisted wires as illustrated in figure 4d. To that end the screwing module 31 can be clamped upon the end of the drive shaft 7 by means of a socket screw 8. The screwing module 31 comprises an axial cavity 32 having a shape which is suitable to receive a wire connector 17, the reception of which is facilitated by a guiding portion 33. In that way the wire connectors 17 can be screwed over the twisted bare wire ends driven by the electromotor of the device shown in figures 1 and 2. Figure 8 shows an embodiment of a stripper module having cutting blades 21 (see also figures 5 a -d) arranged for cutting (e.g.) two different wire diameters e.g. 1½ and 2½ mm2 (equivalent to 14 and 16/17 AWG = American Wire Gauge) ,
instead of -as the embodiment shown in figure 5b- for one wire diameter.
Both cooperating cutting edges 22a surround a cutting hole 34a having a diameter of 1½ mm2 (14 AWG) ; the cutting edges 22b surround a cutting hole 34b having a diameter of 2½ mm2 (16/17 AWG) .
Figure 9 shows a twister module 3 equal to the embodiment shown in figure 3a, however, comprising an operation axial cavity 35 having a slightly conical shape instead of
cylindrical, as in figure 3a. It is noted that a mainly cylindrical bore 9, as shown in figure 3a, may be preferred because the integration or packing quality of bare wires twisted together within a cylindrical twister cavity 9, resulting in a well packed, mainly cylindrically twisted wire assembly, is -at least theoretically- superior to the quality of a conical twisted wire assembly. Figure 10 shows an embodiment of the device, to be used as a "twister-bit" together with an external drive (not shown) , like a standard "cordless drill". The reference signs refer to the same parts as in the previous figures 3a and 9.
However, the drive shaft 7, preferably, has a hexagonal cross-section, as usual to screwdriver-bits. As may be clear, in this embodiment the (complete) twisting device is
constituted by a rotatable twister module 3 and the drive shaft 7, which is arranged to be connected -in the same way as screwdriver-bits- to an external electric drive tool like a cordless drill.
Figures lla-b show two embodiments of the twister cam 13. The twister cam 13 could e.g. be formed in the twister module
body 3, together with the cavity 9, e.g. by means of spark erosion. However, the twister cam 13 can also be made by inserting, into the twister module body 3, an axial
(cylindrical) shaft 36 (figure 11a) or transverse shaft 37 (figure lib), the extremity of which extending (e.g. some millimetres) within the (cylindrical) cavity 9.
Finally it is noted that the wire twisting area extends, seen from the bottom of the cavity 9, over only a fraction of the axial length of said operational area. The wire area to be twisted may have a length of about 15 - 20 millimetres.
However, the height of the wire twisting area or the twister cam(s) 13, measured from the bottom of the cavity 9 may e.g. be between about 3 and 6 millimetres and may e.g. protrude about 2 - 4 millimetres from the side wall. Preferably the height of the twister cam is about 3 mm and protrudes about 3 mm from the side wall. By using a fraction (e.g. 2 - 5 mm) of the axial length of said operational area (e.g. 15 - 20 mm) the twisting device is very suitable to be driven by an electromotor, due to the minimal motion (relative to the wires) of the device in longitudinal direction during the twisting action, caused by the short twister cam(s) , as well as the minimal friction and deformation effects between the wires reciprocally and between the wires and the twister head.