System and method for perforating and removing a foil from electrical cables

Abstract

The invention provides a perforating device (100), for perforating a foil (12) of an electrical cable (10). The perforating device comprising a (cable) support (110), a perforation unit (120), and a swivel arm (130). The support is configured to support a segment of the electrical cable (10) in which the foil (12) is to be perforated. The perforation unit (120) comprises a needle (121) arranged to perforate the foil (12), and a guide (122) arranged to determine a piercing depth of the needle (121). The perforation unit (120) is positioned on the swivel arm (130) such that, when the swivel arm is in an engaged position for perforating the foil (12), the guide (122) abuts the foil of the electrical cable (10).

Description

[0001] System and method for perforating and removing a foil from electrical cables

[0002] This invention relates to a system for perforating and removing a foil from an electrical cable, according to the pre-amble of claim 1. The invention furthermore relates to a method for perforating and removing such a foil.

[0003] Electrical cables, such as multi-core data cables, typically comprise one or more inner or core (copper or aluminium) wire(s) having an inner insulation coating. These inner wire(s) are usually wrapped by one or more foils. Depending on the number of inner wires, the wrapped multi-core part of the electrical cable tens to have a non-circular symmetric cross section. These cables may be screened electromagnetically applying a braid positioned around the foil(s) to ensure high quality data transmission. Finally, an external sheath provides insulation and mechanical protection to the cable.

[0004] When such cables are processed, for instance to be connected to a male or female connector, the outer cable layers, including the foil(s), need to be removed for providing access to the core wires.

[0005] Today's standard foil removal devices use, for example, serrated form knives that pierce the foils at defined points. These methods require a knife with a form-factor typically having a concave shape, such as a semi-circular or arc shape, adapted to the inner wire diameter. In other words, disadvantageously, each cable type requires a different serrated knife to be assembled on the foil removal device. Moreover, in case of non-circular symmetric cross sections of the wrapped multi-core part, these methods have great difficulty in piercing the foils "in between" the inner wires. That is to say, when multiple core wires are wrapped, the foil may abut a first core wire as it loops around it, then extends in between the first core wire and a second core wire before looping around the latter, and depending on the number of core wires, extends to a third core wire or back to the first core wire. The foil, as it extends in between the inner wires, is ill positioned to be pierced by the serrated form knives. US2016322792A1 describes an example of a cable processing device for removing a screening film or foil from a screened multi-core round cable which includes four knives radially movable relative to the cable for cutting into the screening film / foil. Each knife is associated with a cable core of the round cable. The knives have concavely formed cutting edges and guide elements. These guide elements have guide sections in which the cable cores, encased by the screening film, are receivable. The knives protrude relative to the guide elements - at least in a region of the guide sections - by a projection length. The guide sections have a concave circularly cylindrical shape and form a concave abutment surface adapted to the cable core form factor.

[0006] As a further disadvantage the serrations on the knife edge are fixed, both in size and distance to each other. Consequently, this not only results in a non-adjustable penetration depth into the foil(s), it also results in a non-adjustable number of perforations along a foil's circumference. The former complicates the processing of cables with similar geometry but having a different number of foils. The latter complicates the tearing of the foil in a subsequent foil removal process, especially as more and more plastic foils are being used. These plastic foils, made for example from PP (polypropylene) or PETP (polyethylenterephtalat), can be torn only with great difficulty when the number of perforations is limited (as is the case with the prior art serrated form knives, for example). Optionally, a metal layer (for instance aluminium) may have been applied to the plastic foil, usually on a side facing the inner wires. The total thickness of the foil, i.e. plastic with / without metal layer, typically is in the 0.25 - 0.40 mm range. Alternative to plastic based foils, so-called all-metal foils can be applied. These later foils comprise a metal film only.

[0007] The inventors recognised that the above-mentioned problems can be mitigated by an adjustable number of perforations around the entire circumference of the foil, i.e. not only in those parts of the foil that abut or loop around the inner wires, but also in the foil-extensions in between the inner wires. In addition, the inventors recognise the need for a perforating device in which the penetration depth of any means for creating the perforations is adjustable. The invention intends to alleviate at least one of the above-mentioned drawbacks of the prior art, respectively to provide a solution to the identified needs.

[0008] The objective of the invention is solved by the features of the independent claims. Advantageous further developments are shown in the figures and in the dependent claims. According to an aspect of the invention, a perforating device for perforating a foil of an electrical cable (such as a multi-core data cable) is provided comprising: (i) a (cable) support configured to support a segment of the electrical cable in which the foil is to be perforated; (ii) a perforation unit comprising a needle arranged to perforate the foil, and a guide arranged to determine a piercing depth of the needle; and (iii) a swivel arm. In the perforating device according to the invention, the perforation unit is positioned on the swivel arm such that when the swivel arm is in an engaged position for perforating the foil, the guide abuts the foil of the electrical cable with a guide (abutment) surface. Advantageously, mounting the perforation unit on the swivel arm allows the guide to slide over the foil of the electrical cable. For instance, when the electrical cable is rotated along its length axis while the perforating device is fixedly positioned. Or alternatively, when the electrical cable is fixedly held and the perforation device is rotated around the cable. Especially when the electrical cable has a non-circular cross section, such as is the case with many multi-core data cables, the swivel arm allows the perforation unit to deflect while maintaining abutment of the later with the cable foil.

[0009] In an embodiment of the perforating device, the guide is arranged to be positionable in a length direction of the needle for determining the piercing depth of the needle. Preferably, the guide is positionable using a guide setting element, for example, positioning or setting screws (preferably allowing toolless tightening / loosening), an electronic control, a spindle drive, a very hard spring. Advantageously, positioning de guide relative to the needle allows controlling the piercing depth when implementing a constant needle stroke length mechanism.

[0010] In another embodiment, the perforation unit further comprises an excentre and a motor for driving the excentre, wherein the excentre is arranged to determine a stroke length of the needle. Advantageously, the excentre and rotatable motor combination is an elegant mechanism implementing a constant needle stroke length.

[0011] In yet another embodiment of the perforating device, the motor is arranged to control a rotary speed of the excentre. Advantageously, this allows to control the total number of perforations as the electrical cable is rotated along its length axis. The number of perforations may be adapted in dependence of the electrical cable type, respectively the foil type or foil material it contains, to be processed.

[0012] In a further embodiment of the perforating device, the swivel arm comprises a load unit for determining a (mechanical) contact pressure between the guide (respectively the perforation unit) and the foil of the electrical cable. Advantageously, a (predetermined contact pressure allows compensation or correction for electrical cables in which the foil is not tightly wrapped around the inner core(s). Non-tightly wrapped foils typically display a wavy or undulating foil structure in which foil parts may even be bend overlapping each other. With a (pre-determined positive) contact pressure such undulations or foil-overlappings may be corrected when the guide slides over the foil upon rotation of the electrical cable along its length axis. Advantageously, the contact force with which the guide's abutment surface presses against the foil is in the range 10 - 35 N, preferably in the range 15 - 30 N, preferably still in the range 20 to 25 N, such as 22N or 23 N.

[0013] In an embodiment, the load unit comprises a mass or weight arranged to positionable relative to a pivot point of the swivel arm. The mass may be manually positioned. Alternatively, the position of the mass may be electronically controlled. Advantageously, positioning / re-positioning a mass allows to change the moment exerted by the swivel arm. The positioning / re-positioning of the mass may be done manually by an operator of the perforating device, or electronically controlled through an actuator re-positioning a slidable or rotatable mass.

[0014] Further advantages, features and details of the invention will be apparent from the following description, in which embodiments of the invention are described with reference to the drawings.

[0015] In another embodiment, the load unit comprises an actuator. Optionally, the actuator is a pneumatic cylinder; an electric linear motor; an electric motor with a gear and a rack; or a mechanical spring. Advantageously, the actuator allows the swivel arm to be positionable between an engaged position in which the perforation unit abuts the foil to be perforated, and a disengaged position which allows introduction, respectively removal of the electrical cable to be processed. In an embodiment, the actuator is controllably arranged to determine the contact pressure between the perforation unit on the foil.

[0016] According to a second aspect, the invention provides a cable processing machine, for processing electrical cables, comprising a perforating device as described above, and further comprising a cable holding unit arranged to insert or retract the electrical cable into / from the perforating device.

[0017] In an embodiment, the cable holder is arranged to rotate the electrical cable along its length axis. In another embodiment, the perforating unit rotates around the cable, which is held fixed. In a variant, the perforating device comprises three perforating units positioned on a circle at 120° from each other centred at the cable. Advantageously, these three perforating units only need to rotate around the cable over 120°, rather than a full 360°.

[0018] In another embodiment, the cable processing machine comprises a cable gripper arranged to twist and / or bend the electrical cable for tearing-off an end portion of a perforated foil.

[0019] According to a third aspect, the invention provides a method for perforating a foil of an electrical cable, the method comprising: (i) inserting an end portion of the electrical cable exposing the foil along a length axis of the electrical cable into a perforating device comprising a needle configured to perforate the foil; (ii) adjusting a piercing depth of the needle; (iii) operating the needle in a direction substantially perpendicular to the electrical cable's length axis for perforating the foil; and (iv) rotating the electrical cable for perforating the foil around a circumference of the electrical cable.

[0020] In an embodiment, the method further comprises gripping an end portion of the perforated foil, and bending and / or twisting the electrical cable for tearing-off the foil's end portion.

[0021] The list of reference signs as well as the technical content of the patent claims and figures are part of the disclosure. The figures are described coherently and comprehensively. Identical reference signs indicate identical components, reference signs with different indices indicate functionally identical or similar components.

[0022] The figures show:

[0023] Fig. 1A&B schematic perspective view and side views of multi-core cables (2-wire and 4-wire variants);

[0024] Fig. 2A&B a perforating device according to a first embodiment of the invention;

[0025] Fig. 3A&B a perforating device in a disengaged position (A) and in an engaged position (B);

[0026] Fig. 4A&B a detail of the perforation unit with the guide in a position enabling a low needle piercing depth;

[0027] Fig 5A&B a detail of the perforation unit with the guide in a position enabling a high needle piercing depth;

[0028] Fig 6A&B a perforating device according to a second embodiment of the invention; in a disengaged position (A) and in an engaged position (B).

[0029] Fig.l schematically depicts a perspective view and corresponding side views (at 90° to each other) of multi-core electrical cables during an intermediate processing step of the cable prior to removal of the foil. Fig. 1A depicts a two-core-wire electrical cable 10. Fig. IB depicts a four-core- wire electrical cable 10. The core or inner wires

[0030] 11 each have their own inner insulation. The two, respectively four, inner wires are wrapped by foil 12. Around foil 12 an electrical braid 13 is positioned. In the figures, braid 13 has been folded backward over outer insulation 14. In a next processing step foil 12 need to be removed. Advantageously this is realisable by perforating foil

[0031] 12 in a manner where both the perforation depth and the number of perforations along the cable circumference is easily adjustable to the specific cable type.

[0032] Fig. 2A and Fig. 2B schematically show an example of a perforating device 100 according to the invention. It comprises a support 110 for supporting a segment of electrical cable 10 to be processed. Furthermore, perforating device 100 comprises perforation unit 120. The latter is positioned on a swivel arm 130 pivotally arranged around swivel axis 131, and comprises a needle 121 for perforating foil 12. This needle is drivable over a needle stroke length when perforation unit 120 is in an engaged position. Preferably, the needle stroke is in a direction essentially perpendicular to the electrical cable axis. A motor 126, in combination with an excentre 124 and an excentre plate 125, enables the stroke of needle 121. Advantageously, this combination also allows to control the rotary speed of the excentre. With a constant rotation of electrical cable 10 around its axis in support 110, controlling the rotary speed of the excentre allows adjusting the number of foil perforations around the circumference of the cable. Given the needle stroke length defined by excentre 124, perforating device 100 comprises a guide 122 for determining the perforation depth of needle 121. The position of guide 122 in a direction along the length of needle 121 can be controlled by guide setting element 123.

[0033] Fig. 3A and Fig. 3B show perforating device 100 in a position disengaged from electrical cable 10, respectively in an engaged position with electrical cable 10. A load unit 140 allows transferring perforating device 100 from the first to the second position (and vice versa) by pivoting swivel arm 130 about swivel axis 131. Load unit 140 may comprise actuator 141, such as a pneumatic cylinder, an electric linear motor, a gear and rack combination, or a spring. Advantageously, load unit 140 may be operated to determine the contact pressure between guide 122 and foil 12. Rotating electrical cable 10 around its length axis in between support 110 and guide 122 allows the latter to slide over foil 12. Advantageously, even with non-circular symmetric cable types (see Fig. 1A), the swivel arm 130 pivots to maintain a constant contact pressure as cable 10 is rotated over 360°. This enhances not only the quality of the perforations, especially for piercing the foil "in between" the inner wires, it also prevents damage to the inner wires by maintaining an appropriate perforation depth.

[0034] Fig. 4A and Fig. 4B show a detail of perforating unit 100, 200 with guide 122, 222 in a position enabling a small needle piercing depth. Fig. 4A shows the perforating unit with excentre 124, 224 in an upward position, resulting in needle 121, 221 to be retracted from cable 10. Fig. 4B shows the perforating unit with excentre 124, 224 in a downward position, resulting in needle 121, 221 to be engaged with cable 10. The excentre 124, 224 advantageously determines a stroke length of needle 121, 221. The piercing depth of needle 121, 221 can advantageously be controlled through positioning guide 122, 222. Controlling the position of guide 122, 222 in a length direction of needle 121, 221 may advantageously be done using guide setting element(s) 123, 223. This may be implemented, for example by manual operable setting screws. Alternatively, guid setting element 123, 223, may comprise an electronically controllable spindle and associated spindle drive. Alternatively still, guide setting element 123, 223 may be a spring having a large spring constant. Guide 122, 222 in Fig. 4 is positioned so as to enable a small perforation depth.

[0035] Fig. 5A and Fig. 5B show a detail of perforating unit 100, 200 with guide 122, 222 in a position enabling a large needle piercing depth. Fig. 5A shows the perforating unit with excentre 124, 224 in an upward position, resulting in needle 121, 221 to be retracted from cable 10. Fig. 5B shows the perforating unit with excentre 124, 224 in a downward position, resulting in needle 122, 222 to be engaged with cable 10. Guide 122, 222 in Fig. 5 is positioned so as to enable a large (or at least larger) perforation depth. Similar to Figs. 4A and 4B, operating guide setting element 123, 223 to adjust the needle perforation depth should be in compliance with the thickness of foil 12 (or the number of foils to be perforated) and adjusted such that the inner wires are not damaged.

[0036] Fig. 6A and Fig. 6B show a second embodiment of the perforating device 200 according to the invention. Where perforating device 200 comprises similar components incorporated in perforating device 100, these will be identifiable by their reference number (100-series vs. 200-series). Fig. 6A shows perforating device 200 in an engaged position, enabling needle 221 to perforate foil 12 of electrical cable 10. Fig. 6B shows perforating device 200 in a disengaged position. Perforating device 200 can be transferred from the engaged position into the disengaged position with actuator 241. In this case, actuator 241 is a push-rod positioned between pivot point 231 of swivel arm 230 and support 210 for supporting a segment of electrical cable 10 where for foil 12 needs to be perforated. As a load unit 240, a simple weight 242 is applied. Preferably mass 242 is positionable relative to swivel axis 231. Changing the distance between the centre of mass of weight 242 to the pivot point provides a simple method to control the contact pressure of the perforating unit on the foil. Weight 242 may for this purpose be slidably positioned on swivel arm 230. Alternatively, load unit 240 may comprise several weights 242 as well as several positioning points for these weights along swivel arm 230. The positioning points may be recesses into which (one or more of) weights 242 may be positionable. Alternatively, the positioning points may be suspension points onto which (one or more of) weights 242 may be positionable. Weight(s) 242 may be re-positionable manually, or may be repositionable using an actuator controlled by a central controller of the perforating device 200 or cable processing machine 1. Thus, with push-rod 241 in a retracted position, the (relative) position of weight 242 determines the (mechanical) contact pressure with which guide 222 presses against and slides over foil 12 as cable 10 is rotated.

[0037] As will be clear to the person skilled in the art, the embodiments and methods shown in the figures or described herein may also be combined and interchanged within the concept of the invention. Thus, similar to perforating device 100, the perforation depth of needle 221 in perforating device 200, may be controlled by setting guide 222. Moreover, a cable processing machine 1, comprising any of the embodiments of the perforating device described above, may further comprise a cable holding unit for engaging, respectively disengaging cable 10 with perforating device 100, 200, and in particular with cable support 110, 210 for supporting an end-segment of cable 10 to be processed. The cable holding unit may be arranged to rotate cable 10 around a length axis of cable 10. Preferably, the rotation speed is adjustable. In a variant, the cable holding unit fixedly holds cable 10, while perforating device 100, 200 is arranged to rotate around the cable length axis. In a further variant, the perforating device comprises three perforating units positioned on a circle at 120° from each other centred at the cable. Advantageously, these three perforating units only need to rotate around the cable over 120°, rather than a full 360°. Or alternatively, when the three perforating units are fixedly positioned, cable 10 only needs to rotate over 120°.

[0038] In a forth aspect of the invention, a perforating device for perforating a foil of an electrical cable (such as a multi-core data cable) is provided comprising: (i) a (cable) support configured to support a segment of the electrical cable in which the foil is to be perforated; (ii) a perforation unit comprising a needle arranged to perforate the foil, and a guide arranged to determine a piercing depth of the needle; wherein the needle and guide are arranged to be translationally movable relative to each other in the perforation unit. In an engaged position for perforating the foil, the guide abuts the foil of the electrical cable with a guide (abutment) surface. Advantageously, translational ly moving the needle and guide relatively to each other allows to extend a needle point beyond the guide surface and hence penetrate the foil as the later abuts the foil. Thus, in a first embodiment, the guide is (controllably) positioned in the perforating unit while the needle is (repetitively) translated back and forth relative to the guide. In a second embodiment, the needle is (controllably) positioned in the perforating unit while the guide is (repetitively) translated back and forth relative to the needle. The (repetitive) movement of the needle, respectively the guide, may be realised through an appropriate actuator, such as an excentre. In a further embodiment, the needle and guide are arranged on a swivel arm of the perforation unit, similar to what has been described above in relation to the first aspect of the invention. In yet a further embodiment, a cable processing machine, comprising any of these embodiments of the perforating device, may be arranged to rotate the perforating device around a fixedly held electrical cable. Preferable, the rotary speed with which the perforating device rotates around the electrical cable is controllable for adjusting the number of perforations per unit length around the perimeter of the foil to be perforated and removed. Alternatively, the rotary speed is pre-determined while the speed of the (repetitive) movement is controllable.

[0039] List of reference signs

[0040] I Cable processing machine

[0041] 10 Electrical Cable

[0042] II Inner wire(s), including insulation

[0043] 12 Foil

[0044] 13 Braid

[0045] 14 Outer insulation

[0046] 20 Cable holding unit

[0047] 30 Cable gripper

[0048] 100 Perforating device

[0049] 110 Support, for supporting a segment of the cable

[0050] 120 Perforation unit

[0051] 121 Needle

[0052] 122 Guide, for determining a needle piercing depth

[0053] 123 Guide setting element

[0054] 124 Excentre

[0055] 125 Excentre plate

[0056] 126 Motor

[0057] 130 Swivel arm

[0058] 131 Swivel axis

[0059] 140 Load unit, for determining a contact pressure of the perforating unit on the foil

[0060] 141 Actuator

[0061] 200 Perforating device

[0062] 210 Support, for supporting a segment of the cable

[0063] 220 Perforation unit

[0064] 221 Needle

[0065] 222 Guide, for determining a needle piercing depth

[0066] 223 Guide setting element Excentre Motor Swivel arm Swivel axis Load unit (weight) Actuator Mass

Claims

Claims1. A perforating device (100, 200), for perforating a foil (12) of an electrical cable (10), comprising:A cable support (110, 210) configured to support a segment of the electrical cable (10) in which the foil (12) is to be perforated;A perforation unit (120, 220) comprising a needle (121, 221) arranged to perforate the foil, and a guide (122, 222) arranged to determine a piercing depth of the needle; and A swivel arm (130, 230);Wherein the perforation unit (120, 220) is positioned on the swivel arm (130, 230) such that when the swivel arm is in an engaged position for perforating the foil the guide (122, 222) abuts the foil (12) of the electrical cable (10).

2. The perforating device (100, 200) according to claim 1, wherein the guide (122, 222) is arranged to be positionable in a length direction of the needle (121, 221) for determining the piercing depth of the needle.

3. The perforating device (100, 200) according to claims 1 or 2, wherein the perforation unit further comprises an excentre (124, 224) and a motor (126, 226) for driving the excentre, wherein excentre is arranged to determine a stroke length of the needle (121, 221).

4. The perforating device (100, 200) according to claim 3, wherein the motor (126, 226) is arranged to control a rotary speed of the excentre (124, 224).

5. The perforating device (100, 200) according to claim 1, wherein the swivel arm (130, 230) comprises load unit (140, 240) for determining a contact pressure between the guide (122, 222) and the foil (12) of the electrical cable (10).

6. The perforating device (200) of claim 5, wherein the load unit (240) comprises a mass (242) arranged to positionable relative to a pivot point of the swivel arm.

7. The perforating device (100) of claim 5, wherein the load unit (140) comprises an actuator (141).

8. A cable processing machine (1), for processing electrical cables (10), comprising a perforating device (100, 200) according to any of the claims 1 to 7, and further comprising a cable holder arranged to insert or retract the electrical cable into / from the perforating device.

9. The cable processing machine (1) according to claim 8, wherein the cable holder is further arranged to rotate the electrical cable along its length axis.

10. The cable processing machine (1) according to claim 8 or 9, further comprising a cable gripper arranged to twist and / or bend the electrical cable for tearing-off an end portion of a perforated foil.

11. A method for perforating a foil (12) of an electrical cable (10), the method comprising:Inserting an end portion of the electrical cable (10) exposing the foil along a length axis of the electrical cable into a perforating device (100) comprising a needle (121) configured to perforate the foil;Adjusting a piercing depth of the needle (121);Operating the needle (121) in a direction substantially perpendicular to the electrical cable's (10) length axis for perforating the foil (12);Rotating the electrical cable (10) for perforating the foil (12) around a circumference of the electrical cable.

12. The method according to claim 11, further comprising gripping an end portion of the perforated foil (12), and bending and / or twisting the electrical cable (10) for tearing-off the foil's end portion.

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