Patent Application
20180323588
The present invention relates to a cable stripping tool for electrical cables, and in particular to a tool for stripping and preparing cables for securing to a connector for connection to an electricity meter.
Smart meters enable the measurement and recording of electrical energy consumption of and provide the facility to communicate that information on a real time basis to the consumer. The traditional means of metering electricity usage provides a cumulative measure of consumption that doesn't allow the user to appreciate the varying levels of usage over the time. The information provision of consumption data by smart meters enables users to more easily monitor their consumption and to modify their usage if required. Smart meters also enable consumption data to be communicated directly to the energy companies for monitoring and billing purposes. This ability for direct reporting removes the need for the traditional model of physical meter reading by the utility companies.
Given the clear advantages of smart meters, there has understandably been a move to increase smart meter usage, with a target having been set of smart meters installed in all homes in the UK by 2020. The significant increase in the number of smart meter installations has led to the development of guidelines to ensure that meter installation is performed in a manner that is safe and secure for the installer. Under these guidelines an installed meter must be tamper free and present no risk to the consumer. In particular the opening through which the electrical cables are inserted into the meter must be of sufficient size to accommodate the cable, while also preventing the insertion of additional cables or foreign objects into the meter. As electrical cables can vary is diameter, it is not possible to provide a smart meter casing having a universal opening that satisfies both these requirements. It is also a requirement of the installation guidelines that the electrical cables are clearly marked with an indication of their electrical state i.e. whether the cables are ‘live’ or ‘neutral’, as well as an indication of whether the cables are outgoing or incoming; outgoing cables should be provided with two separate markers incoming cables with a single marker. The current practice of marking cables using cable ties is undesirable as it generates material wastage and debris at the point of use. In addition the rotational position of the cable ties about the cables is not able to be fixed, which prevent the ties from being readable. Furthermore it is also not possible to remove and relocate cable ties as removal requires the ties to be cut.
The applicant has developed a cable marker and connector arrangement for use in smart meter installation as described in further detail below. The cable marker for cables having a plurality of inner cables surrounded by an outer sheath, comprises a marker element comprising a collar having an external indicia for indicating the electrical state of the cable to which it is connected, and an internal channel extending therethrough between first and second openings at corresponding first and second ends of the collar, the first opening having a first diameter and the second opening having a second diameter less than the first diameter, wherein the channel is stepped in diameter along its length between the first and second diameters, the step in diameter defining an internal abutment to prevent passage of a cable sheath while allowing the internal cables to pass through to the second opening.
In this way, the first marker element forms a cap for the end of the cable arranged such that the inner cables are not visible or accessible at the first end which in use remains external to the meter. The second end is configured to be inserted into the opening of the meter corresponding to the relevant cable, and as such the free ends of the inner cables are externally shielded and only exposed within the enclosure of the meter. The second end is preferable configured to be received in the corresponding opening of the enclosure with a close tolerance fit, which may be an interference fit, and includes a tapered leading edge to facilitate insertion. This cable marker arrangement requires the cable to be stripped in a stepped manner which is compatible with the cable marker. The exponential increase in the number of smart meter installations requires the installer to be able to strip the electrical cables in a consistent and accurate manner while also doing so as quickly and efficiently as possible.
According to the present invention there is provided a cable stropping tool as described in the accompanying claims.
In an embodiment of the invention there is provided a cable stripping tool for use with electrical cables including an inner core and an outer sheath, the cable stripper comprising a body including a cable retaining portion having a rotational axis defined therethrough. The cable retaining portion is configured to receive a cable such that its longitudinal axis is coaxial with the rotational axis. First and second cutting blades are provided which are movable transversely relative to the rotational axis between a retracted position and a cutting position. The cutting blades each have a blade edge. The blade edges of the first and second blades are axially spaced from each other relative to the rotational axis. The blade edges are also arranged such that in the cutting position the first cutting blade is spaced a first radial distance from the rotational axis and the second blade is spaced a second radial distance from the rotational axis that is greater than the first radial distance. The cable stripping tool is rotatable about the rotational axis when the cutting blades are in the cutting position to cause the blades to cut around the entire circumference of the cable.
The radial spacing of the blade edges in the cutting position allows the first cutting blade to be arranged to cut through both the inner and outer sheathes of the cable to the radial depth of the core while the second blade cuts through only the outer sheath. As the blades are axially spaced, once the full cut has been made the inner sheath is cut at the axial position of the first blade, exposing beyond it the inner core. The inner sheath extends to a greater axial length than the outer sheath, which is cut at the axial position of the second blade at a position spaced further along the cable. This forms a stepped arrangement in which the diameter of the cable steps down to that the of the outer surface of the inner sheath at a first axial position, and then steps down to a second diameter corresponding to the diameter of the inner core. The ability of the tool to rotate about the around the rotational axis enables the cutting blades to cut around the entire circumference of the cable once the blades have made the initial insertion on movement to the cutting position.
The stepped configuration of the stripped cable conforms to the inner configuration of the cable markers. The step defined by the cut between the outer surface of the outer sheath and the outer surface of the inner sheath that exposes the inner sheath locates and abuts a first abutment surface within the cable marker. The second step defined by the cut through the inner sheath to the core seats against a second abutment surface within the marker, inwardly of the first abutment surface. This double stepped arrangement within the marker makes it extremely difficult if not impossible to access the core of the cable through the cable marker, thereby ensuring the electrical core is unable to be accidentally or intentionally contacted once the connection portion of the cable marker is inserted into and connected to the housing of electrical meter. The two step arrangement also ensures that the point along the cable at which the core is exposed is spaced inwardly into the cable marker/connector passed the first abutment surface. The arrangement of the blades of the stripping tool ensures a consistent, clean and reproducible cut that ensures the cable always closely and safely fits into the connector. This is especially important where the tool may be used by a non-skilled or newly trained operator as it allows them to produce the required finish on the cable without difficulty.
The cable retaining portion preferably includes a stop member arranged to longitudinally locate the cable when inserted into the cable retaining portion. The stop member enables the cable to be inserted to a consistent and repeatable axial location. This ensures that the length of exposed core created by the removal of the inner sheath is always the same.
Preferably the first cutting blade is arranged longitudinally towards the stop member relative to the second cutting blade. This ensures that the cuts into the inner and outer sheaths are made in the correct order to achieve the required stepped arrangement. The cable retaining portion may comprise a channel extending into the body section having an opening at located at one end for receiving the cable and the opposing end being closed forming the stop member. The cable is inserted into the cylindrical channel which has a diameter substantially equal to the diameter of the cable such that the walls if the channel laterally restrain the cable during cutting. The closed end of the channel may be formed by a wall of the body section or a cap covering the end. The closed end prevents through insertion of the cable and as such defines the stop member. The cable receiving channel preferably comprises a plurality of longitudinally extending and annularly spaced ribs. The inner edges of the ribs define a diameter that is substantially equal to the diameter of the cable. The cable sheath is able to expand in a more consistent manner into the recesses defied by the gaps between the ribs when compressed by the cutting blades. Compression in only a single direction would result in the cable having an oval form which would prevent even cutting on rotation. The ribs therefore achieve a more even cut.
The cable stripping tool may further comprising a blade actuator pivotally mounted to the body section, wherein the cutting blades are mounted to the blade actuator and pivoting of the blade actuator relative to the body section moves the cutting blades between the retracted position and the cutting position.
The body section preferably includes a cylindrical wall defining an aperture through the body section having an axis parallel with and spaced from the rotational axis, the blade actuator being pivotally mounted about the cylindrical wall.
The cable stripping tool may further comprise a stop member arranged to limit rotational movement of the blade actuator between the retracted position and the full cutting position. The stop member preferably extends from the cylindrical wall and is received with a corresponding channel in the blade actuator having a length defining the stop limits.
The cylindrical wall is preferably configured to receive a user's finger and the inner surface defines curved contact surface to be engaged by the user's finger to rotate the tool around the cable.
The cutting blades are preferably circular and arranged concentrically with the first cutting blade having a diameter greater than the second cutting blade, the central axis of the blades being parallel with the rotational axis.
The cutting blades are preferably spaced from the pivotal axis of the blade actuator such that their central axis pivots along an arcuate path that intersects the rotational axis. The blade actuator is housed within the body and includes a trigger portion that projects out of the body section and is arranged to be depressed by a user to move the cutting blades to the cutting position.
The cutting blades may be movable between a retracted position, an intermediate cutting position and a full cutting position, the radial distance of the first and second blades from the rotational axis being greater at the intermediate cutting position than the final cutting position.
The cable stripping tool preferably further comprises a blade actuator to which the cutting blades are mounted and movement of the blade actuator relative to the body section moves the cutting blades between the retracted position, intermediate cutting position and the cutting position, and the tool further includes a releasable locking element arranged such that on movement of the blade actuator from the retracted position to the intermediate position the locking element locks the blade actuator in the intermediate cutting position preventing return to the retracted position, and on further movement of the blade actuator to the full cutting position the locking element locks the blade actuator in the full cutting position preventing return to the intermediate cutting position. The locking element preferably comprises a releasable ratchet arrangement including a first set of teeth connected to the body section and a second set of teeth mounted to the blade actuator, one of the first and second teeth being movable to release the ratchet arrangement.
With reference to the cable marker, the outer surface of the second end of the cable marker collar preferably has a reduced diameter for insertion into the opening the electrical meter enclosure, with the reduction in diameter defining an external abutment shoulder configured to prevent passage of the first end of the collar into the opening with first end extending outwardly of and obscuring the opening in use. As such, even if the second end does not closely fit within the opening to the meter, the opening is covered and obscured by the larger diameter first end of the collar to prevent additional cables or other objects from being inserted.
The channel preferably includes a third diameter section between the first and second diameter sections, the third diameter section having a diameter less than the first diameter and greater than the second diameter, wherein a first abutment shoulder is defined by the step between the first diameter section and the third diameter section, and a second abutment shoulder is defined between the third diameter section and the second diameter section, the first and third diameter sections being configured for accommodating two different sheath diameters. The wider first diameter accommodates larger cables, and preferably has a diameter of 25 mm, with the free end of the sheath abutting the abutment shoulder between the first and third diameter sections. The third diameter section is preferably 16 mm in diameter. 16 mm cables inserted into the collar pass through the first section and are spaced from the wider channel wall of this section. The free end of the sheath then abuts the shoulder defined between the third and second channel sections. The second channel section is only wide enough to accommodate the inner cables. The cable marker arrangement may further include a second marker element configured to be secured to a cable, the second marker element having an external indicia indicating the same electrical state as the indicia of the first marker element, the second marker element configured to be axially slideable along a cable to enable it to be moved into abutment with the first marker element, the first and second marker elements including cooperating locking means to rotationally fix the second mark element relative to the first marker element when the two are brought into axial abutment. The may alternatively or additionally be arranged to axially fix the first and second marker elements. Securing the first and second marker elements rotationally ensures that the indicia of both are visible from the same viewing angle. Axially abutting the first and second marker elements and holding them in this position ensures that it is immediately evident to the installation engineer that two markers are present on the cable, confirming that the cables are outgoing. In contrast, where cable ties are used it is possible that they may slide along the cable such that on first inspection it may appear that only one marker is present in the cable, giving a false impression of the nature of the cable.
One of the first and second marker preferably elements includes an axial projection and the other includes a corresponding axial recess configured to receive the projection arranged such that when the projection is received in the recess relative rotational movement between the two marker elements is prevented. The projection and recess may also be configured to axially secure the two markers together such as by including a close tolerance friction fit.
The projection and recess are preferably arranged to fix the first and second marker elements in a predetermined rotational relationship in which the indicia are arranged in predetermined manner, and preferably in a predetermined rotational relationship such that the indicia of both elements are aligned.
The second marker element preferably comprises a pair of spaced flexible arms interconnected at one end by a bridging section, the free ends of the arms being expandable to receive a cable into the space defined between the two arms. This enables the marker to be secured to the cable in a quick and easy push fit manner that does not require material waste such as in the case of cable ties.
The arms may project from the bridging section in a first section and bend inwardly towards their ends such that the free ends extend in an opposing second direction, the free ends of the arms being located inwardly of the proximal ends of the arms. The free ends flex towards the proximal ends on cable insertion, while the proximal ends also flex outwardly, thereby creating two inwardly directed biasing forces to grip the arms onto the cable. The inner edges of the free ends also face upwardly towards the bridging section when flexed creating an angled biasing force that clamps the cable in position.
The free ends of the arms are spaced from the bridging section.
The free ends of the arms include preferably barbs projecting inwardly and angled towards the bridging section in the second direction, which is in the direction of insertion and opposing the direction of retraction of the cable, to grip and retain a cable received within between the free ends of the arms.
The second marker element preferably further includes a locating arm extending across the space defined between the two arms in a direction substantially parallel with the bridging member and spaced inwardly towards the bridging section away from free ends of the arms, the locating arm being arranged to locate smaller cables in a position where they may be gripped by the free ends of the arms, and being flexible away from the free ends of the arms to accommodate larger cables. The locating arms is preferably curved to accommodate the curved surface of the cable. The arm ensures that smaller diameter cables, and specifically the 16 mm cables are housed closely within the marker element without passing so far in that they are not properly gripped by the gripping arms, and provides a returning biasing force to hold the cable in place. When the larger 25 mm cable are inserted the locating arm flexes away towards the bridging section to provide greater space to accommodate the cable. The locating arm preferably extends from the inner edge of one of the pair of arms, at a position spaced from the bridging section and the free ends of the arms in the insertion direction, and extends laterally relative to the insertion direction towards the other arm, from which it is free and preferably spaced.
The first cable marker element is preferably a single piece molded plastic component and the indicia is integrally molded as part of marker element. The second cable marker element is also preferably a single piece molded plastic component and the indicia is integrally molded as part of marker element. As such the components are cheap to manufacture, and do not require multiple parts that can become separated and/or which require timely assembly at the point of use.
A cable marking kit may also be provided comprising a first pair of first and second cable marking elements as described above having indicia indicating a live cable condition, a second pair of first and second cable marking elements as described above having indicia indicating a neutral cable condition, and a pair of first cable marking elements as described above, one if which has an indicia indicating a live cable condition and the other of which has an indicia indicating a neutral cable condition. There may also be provided a cable marker arrangement comprising a pair of spaced resiliently flexible arms interconnected at one end by a bridging section, the free ends of the arms being expandable to receive a cable into the space defined between the two arms, and configured such that when expanded they impart a returning force to grip the cable.
The arms preferably project from the bridging section in a first section and are bent inwardly towards their ends such that the free ends extend in an opposing second direction, the free ends of the arms being located inwardly of the proximal ends of the arms. The free ends of the arms may include barbs projecting inwardly and angled towards the bridging section in the second direction to grip and retain a cable received within between the free ends of the arms. The second marker element may further include a locating arm extending across the space defined between the two arms in a direction substantially parallel with the bridging member and spaced inwardly towards the bridging section away from free ends of the arms, the locating arm being arranged to locate smaller cables in a position where they may be gripped by the free ends of the arms, and being flexible away from the free ends of the arms to accommodate larger cables.
The locating arm preferably extends from the inner edge of one of the pair of arms and extends towards and is spaced from the other arm. A method of marking cables during installation of an electrical meter comprising:
The outer surface of the second end of the collar of the first marker elements preferably has a reduced diameter for insertion into an opening an electrical enclosure, the reduction in diameter defining an external abutment shoulder configured to prevent passage of the first end of the collar into the opening with first end extending outwardly of and obscuring the opening in use and wherein step a) further includes inserting the second end of the first marker element into the corresponding opening of the enclosure of the electrical meter until the abutment shoulder abuts the surrounding outer surface of the enclosure and securing the free ends of the inner wires to the electrical meter when the first marker element is in the inserted position.
Other characteristics and advantages of the invention shall appear upon reading the detailed description and the appended drawings, in which:
Referring to
In accordance with installation guidelines, the cables 6, 8, 14 and 16 are each provided with a first cable marker 22a-d including an indicia 24a-d indicative of the electrical state of the cable, with a ‘L’ indicating the live cables and a ‘N’ indicating the neutral cables. The outgoing live 14 and neutral 16 cables both include a second cable marker 26c and 26d respectively having indicia 28c and 28d matching the indicia of the corresponding first cable marker 22. The presence of two cable markers indicates to the installer the outgoing cables.
As shown in
As shown in
The stepped reduction in diameter between the first channel section 36 and the third channel section 40 creates a first abutment shoulder 42. Similarly, the stepped reduction in diameter between the third channel section 40 and the second channel section 38 defines a second abutment shoulder 44. When a cable having a 25 mm diameter sheath is inserted into the first marker 22 it is accommodated within the first channel section 36 with the outer walls of the sheath 30 closely engaging the walls of the first channel section 36. One or more projections at 46 may extend radially into the first channel section 36 which locally deform the sheath 30 to key and rotationally lock the first marker 22 on to the cable. The axial end surface of the sheath 30 when fully inserted abuts the first abutment shoulder 42, which acts as a stop and prevents further axial travel of the sheath 30 through the marker 22, as shown in
The first marker 22 is also able to receive a 16 mm diameter cable. In this arrangement the cable is received within the third channel section 42 without engagement with the walls of the first channel section 34. Again the third channel section 40 may include one or more radially extended projections 46 to rotationally restrain the cable. The end surface of the sheath 30 of the cable engages the abutment surface 42 and in the same way as described above prevents axial travel of the sheath 30 past the abutment shoulder 44 while permitting the inner cables 32 to extend through the second opening 40.
As shown in
When the cable is fully received within the second marker 26 the resilient arms 54 in their expanded configuration provide a returning force which clamps the arms against the cable. The compressed distal ends 58 are angled in the flexed form such that the end surfaces angle inwardly in the insertion direction A with the cable being inserted a sufficient distance in to the marker 26 that part of the inner surface of the distal sections 56 engage the rear side of the cable relative to the insertion direction A urging the cable into the second marker 26, with the barbs 68 assisting to prevent retraction of the cable. A locating arm 70 is provided within the marker 26 proximate the bridging section 52. The locating arm 70 has a curved profile and is secured at its base to one of the arms 54 and extends across the void within the marker 26 towards the other arm 54 with the end of the locating arm 70 being spaced from the other arm 54. The locating arm 70 is flexible and able to flex in the insertion direction A towards the bridging section 52. The locating arm 70 provides a stop for smaller 16 mm cables. If such smaller cables were to be inserted all the way into the marker such that they abutted the bridge 52 then they would not be adequately gripped by the distal ends 58 of the arms 54. The locating arm 70 limits insertion of the cable and provides a returning biasing force against the cable in a direction opposing the insertion direction A, thereby clamping the cable between the distal ends 58 and the arm 54 and the locating arm 70. Where a large 25 mm cable is inserted into the marker 26 the locating arm is able to flex rearwardly towards the bridging section 52 to accommodate the larger cable.
As shown in
As shown in
In an alternative embodiment shown in
An alternative cable marker/connector 122 is shown in
When a stepped cable having a 25 mm outer diameter sheath is inserted into the marker 122 it is accommodated within the first channel section 136 with the outer walls of the sheath 30 closely engaging the D4 diameter wall of the first channel section 136. A projection at 147 extends radially into the first channel section 136 which locally deforms the sheath 130 to key and rotationally lock the marker 122 on to the cable. The first abutment shoulder 135 abuts against the first abutment shoulder 142 of the marker 122. The exposed length 127 of the inner sheath having a reduced diameter D2 equal to the diameter D5 of the second channel section 138 extends into the second channel section 138. The length of the second channel section 138 is equal to the length L2-L1 of the exposed inner sheath section 127 such that the second abutment shoulder 137 seats against and abuts abutment shoulder 144 of the marker 122. Similarly where a 16 mm tie is used the first abutment shoulder 135 of the cable 129 seats on the third abutment shoulder 146 of the maker 122 and the second abutment shoulder 137 seats on the final abutment shoulder 148. The length of the fourth channel 145 is equal to the length of the exposed inner sheath section 127. It is important that the cable 129 is accurately stripped at length locations LI and L2 and that at these points the cable 129 is cut to the diameters D1 and D2 respectively. To avoid human error and lack of consistent reproducibility,
The circular blades 162 are rotationally mounted to the blade actuator 166 with their rotational axis 176 being arranged parallel to the longitudinal axis of the channel 154 and such that they are arranged transversely to the longitudinal axis 164. The blades 162 are concentric and coaxial. The first blade 178 has a first diameter D9 and the second blade 180 has a second diameter Di0 that is greater than the diameter D9. The difference in diameters D9 and Di0 is selected such that the blade edge of the second blade 180 is spaced radially outwards from the blade edge of the first blade 178 a distance equal to Di-D2, being the radial thickness of the second abutment shoulder 137 which also corresponds to the thickness of the inner sheath 133 of the cable 129. The blades 178, 180 are axially spaced by a distance equal to the length of the exposed inner sheath section 127.
Rotation of the blade actuator 166 about the wall 172 of the aperture 160 pivots the blades 162 along an arcuate path towards and away from the channel 154 in a plane transverse to the longitudinal axis 164 of the channel 154. When a cable 129 is received in the channel 154 the outer surface of the cable 129 engages the inner edges of the ribs 170 which are sized such that their inner edges define an inner diameter to the channel 154 that is equal to the relevant cable diameter. The blade actuator 166 is configured to pivot the blades 162 to a first cutting position as shown in
In the fully retracted position of the blade actuator 166 the second blade 180 is located at a radial distance from the longitudinal axis greater than or equal to the inner diameter of the channel 154 as defined by the inner edges of the ribs 170 such that a cable 129 may be inserted into the channel 154 with interference with the blades 162. A stop member 182 extends radially outwards from the wall 172. The stop member 182 is received with a channel 184 in the body of the blade actuator 166 defined by a recess in the circular inner wall that surrounds the wall 172. The end walls 186 and 188 of the recess engage with the stop member 182 to limit rotation of the blade actuator 166. The spacing and angular location the end walls 186 and 188 define the stop positions of the fully cutting position and the fully retracted position respectively. As can be seen in the section view of
Referring to
The teeth 194, 196 and 202,204 include corresponding sloping camming surfaces on their leading edges such that as the first tooth 196 contacts the first tooth 202 of the latch the teeth cooperate to slide the latch 200 towards the release position to allow the tooth 196 to move past the tooth 202. Once past the biased latch returns to the locked position and the tooth 196 is latched against tooth 202 in a ratchet manner. The latch 200 and the locking arm 192 are arranged such that this first engagement corresponds to an intermediate rotational position of the actuator 166 in which the blades extend partially into the channel 154 but not to the full cutting position.
With the blades 162 penetrating the sheath 130 of the cable 129 to a partial cutting depth the user grips the cable 129 with a first hand and the inner surface of the wall 172 of the handle 158 with their finger and uses the handle 158 to rotate the tool 150 around the cable 129. The longitudinal axis of the channel 154 defined the rotational axis of the tool 150. Rotation of the tool 150 around the cable 129 causes the blades 162 to effect a fully circumferential cut, meaning a cut that extends a full 360 degrees around the cable. The partial extension of the blades 162 to the intermediate cutting position makes this fits cutting operation easier with deformation of the cable being limited during the cut. The trigger is then further depressed moving the locking arm to a second locking position corresponding to the full cutting position of the blades 162, in which the first locking tooth 196 of the locking arm moves into engagement with the second locking tooth 204 of the latch, and the second locking tooth 194 of the locking arm 192 moves into engagement with the first latch tooth 202. The rotational cutting process is then repeated, with the tool preferably being rotated several rotations to effect a complete cut. Following the second cutting operation the cable may be retracted from the channel 154. Retracting the cable 129 with the blades 162 still in the full cutting position causes the blades 162 to axially retain the cut portions of the sheath within the channel such that the cable is retracted in a fully stripped state. The slide switch 206 of the latch 200 is then operated to return the actuator 166 to the retracted position. This also acts to release the stripped sections of the sheath.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1519506.8 | Nov 2015 | GB | national |
This application is a national stage application under 35 U.S.C. § 371 of PCT Application Number PCT/EP2016/076704 having an international filing date of Nov. 4, 2016, which designated the United States, said PCT application claiming the benefit of Great Britain Patent Application No. 1519506.8, filed Nov. 4, 2015, the entire disclosure of each of which are hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/076704 | 11/4/2016 | WO | 00 |
