Apparatus and method for cutting an end portion of the shielding foil of a shielded electrical cable

Abstract

An apparatus (10) for cutting an end portion (3a) of the shielding foil (3) of a shielded electric cable (1), which covers at least one conductor (2, 20) provided with a covering layer (5, 50), wherein said end portion (3a) of said shielding foil (3) is exposed, is described, said apparatus (10) comprising: a gripping device (11) for gripping said end portion (la), said device (11) comprising an opening (22, 23) for the passage of said cable (1) and being rotatable about a rotation axis (X) passing through said opening (22, 23) to rotate said cable (1) during the cutting operation, drive means (52, 53; M2, M3) for rotating said gripping device (11) with respect to said rotation axis (X); a laser source (18) for carrying out the operation of cutting said end portion (3 a) of the shielding foil (3); movement means (19) configured for moving said laser source (18) at least along a radial direction (Z) with respect to said rotation axis (X), to vary the distance (L) of said laser source (18) from said rotation axis (X) during the cutting operation depending on the variation of the value of the distance (D) of the shielding foil (3) from the rotation axis (X), such value being measured along the straight line joining said rotation axis (X) and said laser source (18).

Description

[0001] “Apparatus and method for cutting an end portion of the shielding foil of a shielded electrical cable”

[0002] * * *

[0003] FIELD OF THE INVENTION

[0004] The present invention concerns an apparatus and method for cutting an end portion of the shielding foil of a shielded electric cable.

[0005] The present invention further concerns a gripping device for gripping a shielded electric cable.

[0006] The present invention is used in the field of shielded electric cables and, in particular, in the field of bipolar or multipolar cables.

[0007] KNOWN PRIOR ART

[0008] Shielded electric cables comprising one or more conductors dielectrically insulated and provided with one or more shielding layers made of electrically conducting material, which act as an electromagnetic shield to cancel or at least limit electromagnetic interference (EMI), are known.

[0009] Cables (e.g. coaxial cables) having a single central conductor usually made of copper, wrapped in a layer of electrically insulating material (a dielectric) usually made of polyethylene or PTFE, which separates the central core from one or more outer shielding layers, are known.

[0010] Generally, the shielding layer comprises a shielding foil of conductive material (known in the art by the English term "foil"), e.g., a thin, preferably multilayer, aluminum- based film that wraps around the layer of electrically insulating material, and a shielding braid that wraps around this underlying foil.

[0011] There is also an outer cable-insulation sheath that encloses the layers and components described above.

[0012] Also bipolar cables, which have two adjacent conductors, each individually wrapped in a respective layer of electrically insulating material (a dielectric), and one or more shielding layers which generally comprise a shielding foil covering the assembly of the two conductors, which are individually wrapped in the layer of electrically insulating material, are known.

[0013] Such bipolar cables also have a shielding braid composed of strands, which surrounds this shielding foil made of conductive material.

[0014] As known, the shielding metal foil can be made, for example, of a preferably multilayered aluminum-based foil having different thicknesses, usually between 0.05 mm and 0.3 mm, though not limited thereto, which is arranged around the dielectric that covers the conductor (or in general one or more conductors) of the shielded electric cable.

[0015] In other words, the foil, constituting an additional shielding of the cable, is generally interposed between the electrically insulating material (dielectric) and the braid.

[0016] As stated, there is a protective sheath usually made of an electrically insulating material on the outside of the shielding braid.

[0017] The shielded electric cables may be further provided with electric connectors connected to the ends of the electric cable. For example, in order to constrain a connector to the end portion of a coaxial or bipolar cable, the end portion of the electric cable must be prepared by carrying out a method which typically comprises the following steps:

[0018] • removing a portion of the outer protective sheath, so as to leave a predetermined length of the shielding braid exposed at an end portion of the electric cable;

[0019] • removing or overturn backwards (i.e., in the opposite direction with respect to the free end or end portion of the cable which is under operation) a portion of the exposed shielding braid, in order to shorten the exposed portion of shielding braid so as to obtain the final part of the cable end portion with the shielding foil exposed;

[0020] • removing a portion of the shielding foil, to shorten the exposed portion of shielding foil so as to obtain the final part of the cable end portion with the dielectric exposed.

[0021] Removing the shielding foil is a crucial operation in the method of preparing the end portion of a shielded electric cable.

[0022] Some methods of the known art perform the removal of the shielding foil by using a laser source.

[0023] The shielded cable is inserted into a support cavity and the end portion comprising the shielding foil to be removed is cut by means of a laser source.

[0024] In known systems, the laser source rotates about the cable to carry out the cutting of the shielding foil or the cable is rotated about a rotation axis while the laser source is held in a fixed position.

[0025] In other words, the apparatuses known in the art provide to rotate the cable and laser source relatively about the axis of the cable, so as to determine the cutting of the foil and separation from the cable.

[0026] The removal of the foil formed by means of such known apparatuses can be non- uniform, i.e. the cutting profile of the foil is not uniform since it depends on the distance of the shielding foil with from the cutting source: in particular, in the case of bipolar cables, i.e. those comprising two adjacent conductive cables, the cable has a variable diameter, in particular, it has an elliptical section with a major axis and a minor axis.

[0027] Moreover, a drawback deriving from apparatuses known in the art is that the devices for gripping and locking the cable available to them generally comprise a couple of elements which are movable between an operating position for locking the cable, in which the cable is held between the couple of locking elements, and a non-operating position for releasing the cable. Such devices are, for example, configured as a clamp. Similar devices generate dead angles with respect to the laser beam when rotated to rotate the cable with respect to the laser source for carrying out the cutting of the foil, with the consequence that different operations for rotating the cable and different passes of the laser beam are necessary for completing the operation of cutting or removing the shielding foil.

[0028] Moreover, the shape of the cavities of the gripping and locking devices is not very suitable for use with cables of non-circular shape, for example with cables of the bipolar type, which do not have a perfectly circular section.

[0029] Object of the present invention is to overcome the drawbacks of the art and in particular those mentioned above in relation to methods that use a laser source for removing the shielding foil, and to provide a method and an apparatus for preparing the end portion of a shielded electric cable that can carry out the cutting and removal of the end portion of the shielding foil with high degree of precision, thus forming a clean and homogeneous cutting profile.

[0030] Further object of the present invention is to provide a method and an apparatus for the end preparation of a shielded electric cable that can carry out the removal of the shielding foil in a uniform way and without risking to damage the foil and / or conductor (or conductors) of the shielded electric cable.

[0031] Further object of the invention is to provide a method and an apparatus for removing the shielding foil of a shielded electric cable that is versatile and usable in combination with different types of shielded cables, in particular with cables of multipolar type. SUMMARY OF THE INVENTION

[0032] These and other objects are achieved by the present invention by means of an apparatus for cutting and removing the end portion of the shielding foil of a shielded electric cable according to the independent claim 1 and a method according to the independent claim 8 and a cable gripping device according to claim 14.

[0033] Further characteristics / aspects of the present invention are described and / or set forth hereunder in the dependent claims. It should be noted at the outset that what is described and / or claimed herein with reference to the method can be applied to the apparatus, and vice-versa.

[0034] The apparatus for removing an end portion of the shielding foil of a shielded electric cable, wherein an end portion of the cable has at least one shielding foil which covers at least one conductor provided with a layer for covering the shielded electric cable (in other words, the shielding foil is placed on the outside the insulating covering layer the at least one conductor is provided with), and wherein at least one end portion of the shielding foil is exposed, comprises: a gripping device for gripping said end portion; said device comprising an opening for the passage of said cable and being rotatable about a rotation axis passing through said opening to rotate said cable during the cutting operation; drive means for rotating the gripping device with respect to the rotation axis; a laser source for carrying out the operation of cutting the end portion of the shielding foil; movement means configured for moving said laser source at least along a radial direction with respect to said rotation axis, to vary the distance of the laser source from the rotation axis during the cutting operation depending on the variation of the value of the distance of the shielding foil from the rotation axis, such value being measured along the straight line joining said rotation axis and said laser source.

[0035] Advantageously, by means of such an apparatus, it is possible to cut portions of shielding foil from a cable of any section without damaging the underlying conductor. In particular, by means of such an apparatus, it is possible to cut portions of shielding foil from a cable that is not coaxial, for example bipolar, and which consequently does not have a circular cross section but which is elliptical or anyhow of a shape such that it does not have a uniform and constant radius but which has at least one minor axis and one major axis.

[0036] In fact, by rotating a cable where the conductors (and consequently the covering shielding foil) are not arranged in such a way that the cable as a whole has a circular cross section, the distance of the shielding foil from the rotation axis of the cable and the focal plane of the laser source consequently varies during the rotation of the cable. It should be noted that the radial direction of the driving of the laser source is preferably said straight line that joins the rotation axis with the laser source. In other words, considering the axis of the laser beam, the laser source can be moved along said straight line.

[0037] According to a preferred aspect, the axis of the laser beam, during the cutting operation, is radial with respect to the rotation axis of the cable. Thanks to this, the thickness of the foil to be cut by the laser is substantially constant.

[0038] In other words, the axis of the laser beam is thus radial to the cable and impacts the foil always in the direction of the thickness. Thanks to this, the foil quantity to be cut by the laser is substantially constant in time, therefore, the laser does not require a variation in the power emitted nor a different maintenance time for different cable zones.

[0039] This simplifies the cutting operations and provides as a further advantage a lower energy consumption.

[0040] It should be noted that focal plane means the plane passing through the focal point perpendicular to the axis of the laser beam, which is located at a distance equal to the focal length of the laser source.

[0041] By means of the present apparatus, it is possible to achieve uniform cutting of the shielding foil, thanks to the combination of the rotation movement of the cable and the translation of the laser source with respect to the rotation axis, which allows to keep the focal plane of the laser source always tangent to the point of the shielding foil to be cut.

[0042] On the contrary, non-uniform cutting of the shielding foil is achieved with the devices known in the art.

[0043] According to an aspect, the apparatus comprises detecting means configured for monitoring in real time the value of said distance of the shielding foil from the rotation axis, which value is measured along the straight line joining said rotation axis and said laser source during the rotation of said cable.

[0044] Advantageously, the detecting means allow to know the shape, position and arrangement of the conductors of the cable being machined, by means, for example, of a camera or other sensors, during the rotation of the cable being cut, and thus allow to displace the laser source in such a way as to keep the proper focal distance from the cutting point.

[0045] This factor allows to minimize damages that could be found on the cable, due to too close of a distance between the laser source and the shielding foil to be cut, and to calibrate the exact and sufficient laser power.

[0046] According to an aspect, the movement means of the laser source are configured for moving the laser source along a radial direction with respect to said rotation axis, whenever said value of the distance detected at a given instant is different from the value of the distance detected at a previous instant.

[0047] It should be noted that the movement means are adapted for moving the laser source in case it is too close or too far away from the shielding foil.

[0048] According to an aspect, the movement means are configured for moving said laser source away from said rotation axis, whenever the value of said distance detected at an instant is greater than the value of said distance detected at a previous instant, and for moving said laser source closer to said rotation axis whenever the value of said distance, detected at an instant, is less than the value of said distance detected at a previous instant.

[0049] Advantageously, the detection of the distance of the laser source from the shielding foil occurs in real time, as the control of the movement means of the laser source occurs in real time during the rotation of the cable. This allows to move the laser source and gripping device for gripping the cable synchronously, which allows the rotation of the cable.

[0050] According to an aspect, the movement means for moving the laser source are configured for varying said distance in such a way that the focal plane of said laser source coincides with the cut plane tangent to said end portion at the cut point of the laser beam during the rotation of said cable.

[0051] According to an aspect, the apparatus comprises an air source which is delivered at a temperature of between -40°C and -20°C and preferably equal to -30°C.

[0052] Advantageously, such low-temperature air source allows to avoid damage produced by the heat generated by the laser beam during the cutting of the shielding foil.

[0053] According to an aspect, the apparatus comprises removal means for removing said end portion of said shielding foil cut by means of said laser source.

[0054] For example, the removal means can comprise a clamp or a suctioning duct for scraps. Removal of the shielding foil means the removal of the foil portion of the end of the cable and, as stated, such removal can advantageously be performed in a simple and quick way by moving the removal means or by suctioning the scraps or a combination thereof.

[0055] According to an aspect, the apparatus comprises a control logic unit electronically connected at least to said drive means for said gripping and / or to said laser source and / or to said movement means for said laser source and / or to said detecting means. The present invention further concerns a method for cutting an end portion of the shielding foil of a shielded electric cable by means of an apparatus according to one of the preceding claims, wherein said shielding foil covers at least one conductor provided with a covering layer, wherein at least one end portion of said shielding foil is exposed, said method comprising the following steps: a) inserting said end portion of said cable into said gripping device and locking it in said gripping position; b) determining the value of the distance of the shielding foil from the rotation axis, such value being measured along the straight line joining said rotation axis and said laser source; c) operating said drive means for rotating said gripping device with respect to said rotation axis to rotate said cable; d) driving said laser source for performing the cutting of said end portion of said shielding foil during the rotation of said cable; e) driving said movement means for moving said laser source so as to vary the distance of said laser source from said rotation axis during said step d) depending on the variation of the value of said distance of the shielding foil from the rotation axis. As discussed above, during step e) the laser source is typically moved in radial direction with respect to the rotation axis of the cable, along the straight line which connects the rotation axis with the laser source, i.e. considering the axis of the laser beam, the laser source is movable along said straight line.

[0056] During step d), the axis of the laser beam is thus typically maintained in the radial direction with respect to the rotation axis of the cable.

[0057] According to an aspect, said step b) is performed by means of detecting means configured for monitoring in real time said value of said distance of the shielding foil from the rotation axis during the rotation of said cable.

[0058] According to an aspect, said step e) is performed whenever said value of the distance detected at a given instant is different from the value of the distance detected at the previous instant.

[0059] According to an aspect, in said step e), said laser source is moved away from said rotation axis whenever the value of said distance detected at an instant is greater than the value of said distance detected at a previous instant, and said laser source is moved closer to said rotation axis whenever the value of said distance, detected at an instant, is less than the value of said distance detected at a previous instant.

[0060] According to an aspect, in which the apparatus comprises a control logic unit electronically connected at least to said drive means for driving said gripping and / or to said laser source and / or to said movement means for said laser source and / or to said detecting means, and wherein said steps b) - e) are performed at least partly by means of said control logic unit.

[0061] The present invention further concerns a gripping device for gripping a cable rotatable about a rotation axis, comprising at least one first rotatable body provided with a first opening for the passage of said cable and comprising presser elements for pressing said cable, and a second rotatable body provided with a second opening for the passage of said cable, said second body having pushing elements adapted for moving said presser elements between at least one gripping position and at least one position for releasing said cable, wherein said first body and said second body are arranged facing one another, in such a way that the respective openings are aligned along said rotation axis, and wherein said second body is rotatable about said rotation axis with respect to said first body or vice-versa, in such a way that said pushing elements act on said gripping elements, which are moved for locking said end portion of said cable in said gripping position.

[0062] Advantageously, a similar gripping device allows the operation of adjustably gripping the cable and the operation of rotating the same contemporaneously.

[0063] According to an aspect, the presser means for said cable are movable, in radial direction with respect to said rotation axis, between at least one gripping position and at least one position for releasing said cable.

[0064] Advantageously, according to such configuration, the device is adapted for machining cables of the coaxial type and the presser means are shaped in a way complementary to the profile of the outer surface of the shielding foil, so as to optimally surround the latter in a closed position.

[0065] Moreover, the device is adapted for machining cables of the type comprising two preferably adjacent conductors and the shape of the presser means is configured to be substantially complementary to the profile of the outer surface of the shielding foil covering these preferably adjacent conductors, which are each equipped with a covering layer, and / or to be substantially complementary to the profile of the outer surface of the covering layer of the two conductors.

[0066] Advantageously, according to such configuration, the device is adapted for being implemented in an apparatus according to the invention for machining cables preferably of the bipolar type.

[0067] The application with cables having a greater number of conductors is not however excluded.

[0068] According to an aspect, the first and the second bodies are integrally rotatable about said rotation axis to rotate said end portion of said cable.

[0069] According to an aspect, the gripping device comprises first operating means for said first rotatable body and second operating means for said second rotatable body, which can be operated independently or contemporaneously.

[0070] According to an aspect, said first rotatable body and said second rotatable body comprise a toothed perimeter profile and said first and second operating means comprise a first and a second toothed shaft, respectively.

[0071] The present invention further concerns an apparatus for cutting an end portion of the shielding foil of a shielded electric cable according to the invention, comprising a gripping device according to the invention.

[0072] BRIEF DESCRIPTION OF THE FIGURES

[0073] Further aspects and advantages of the present invention will become clearer from the following description, which is made by way of example, with purely illustrative and non-limiting reference to the schematic drawings depicted in the accompanying figures in which: figures 1A and IB schematically show side views of the ends of a bipolar cable and of a coaxial cable, which can be machined with the apparatus and method according to the present invention; figure 1C shows the section, according to a plane perpendicular to the axis, of a bipolar cable according to figure 1 A; figures 2A and 2B schematically show a portion of a cable which can be machined in an apparatus according to the invention, comprising a shielding braid; figures 3 and 4 show two perspective views of a possible embodiment of the apparatus for cutting an end portion of the shielding foil of a shielded electric cable according to the invention; figure 5 shows a sectional view of a possible embodiment of the apparatus for cutting an end portion of the shielding foil of a shielded electric cable according to the invention; figure 6 schematically shows a possible step of the method according to the invention, in which the laser source carries out the operation of cutting the shielding foil of the cable rotating about the rotation axis; figure 7 shows a view of the transfer device for transferring the cable; figures 8A and 8B show a front view of the cable gripping device in a first embodiment according to the invention; figure 9A shows a perspective view of the cable gripping device in the embodiment according to the invention of figures 8A and 8B; figure 9B shows an exploded perspective view of the cable gripping device in the embodiment according to the invention of figure 9A; figures 10a and 10b show a front view of the cable gripping device in a second embodiment according to the invention.

[0074] EMBODIMENTS OF THE INVENTION

[0075] Referring to figures 1 A and IB, a shielded electric cable 1 typically comprises at least one central conductor 2, 20 and a shielding braid 4 separated by a layer of electrically insulating material 5, 50, or dielectric, that covers the conductor or conductors 2, 20. As stated, an additional shielding layer consisting of a shielding foil 3, preferably a thin multilayer film made, for example, from aluminum, is arranged between the braid 4 and the dielectric 5, 50.

[0076] For the sake of simplicity, in this document reference will be made only to the conductor 2, 20 of the cable, this term also referring to the covering layer 5, 50 of electrically insulating material with which it is equipped. In fact, the expression “the foil 3 covers the conductor 2, 20” will be used to denote that the foil is placed on the outside with respect to the insulating covering layer 5, 50 with which the at least one conductor 2, 20 of the cable 1 is provided.

[0077] Around the shielding braid 4 there is an outer protective sheath 6, also typically made of electrically insulating material.

[0078] In a possible embodiment shown in figures 3 - 5, the apparatus schematically denoted in the figures as a whole by the numerical reference 10 is adapted to process a cable 1, of the bipolar type and shown in figures 1C and 6, comprising two adjacent conductors 2, 20 each individually wrapped in a respective layer of electrically insulating material (for example a dielectric) 5, 50, and a shielding foil 3 which covers the assembly of the two conductors 2, 20, which are individually wrapped in the respective layer of electrically insulating material 5, 50.

[0079] It should be noted that such a cable, comprising two adjacent conductors, has an elliptical cross section and does not thus have a cross section with a constant diameter or radius.

[0080] In an embodiment shown for illustrative purposes in figure 7, the apparatus 10 comprises a conveying device 17 for conveying said cable 1 and adapted for moving the cable 1 towards the work station. The conveying device 17 can comprise a couple of elements which are movable between an operating position for locking the cable, in which the cable is held between the couple of locking elements, and a non-operating position for releasing the cable. Such conveying device 17 can for example be configured as a clamp and different methods can be used for operating the locking / releasing of the cable, such as hydraulic or pneumatic or electric actuators for example.

[0081] With reference to figures 2A and 2B, in a possible embodiment, the end portion la of the electric cable 1 is typically prearranged by removing a portion, of a given length, of protective sheath 6, so as to leave the shielding braid 4 (if any) of the end portion la of the electric cable 1 exposed.

[0082] Whenever the cable 1 has the shielding braid 4, the cable can be prepared for the successive removal of the foil 3, for example by means known in the art which overturn the shielding braid 4 and are adapted to fold up the end portion of the shielding braid in such a way that the end portion of the underlying foil 3 is exposed.

[0083] In a possible embodiment shown in figure 2B, the exposed part of the shielding braid 4 is preferably locked by locking means 133 adapted for firmly holding a portion of the shielding braid 4, and folded, by means for overturning the shielding braid 4, which are adapted for folding up the end portion 4a of the shielding braid 4 above the locking means 133, in such a way that the end portion 3a of the underlying shielding foil 3 is exposed. The so-prearranged end portion la of the shielded electric cable 1 is thus ready to be subjected to the step of removing the end portion 3a of the shielding foil 3.

[0084] In fact, as a result of overturning the braid, at least one end portion 3 a of the shielding foil 3 is exposed for machining and not covered by the shielding braid 4.

[0085] The apparatus 10 according to the invention, adapted for cutting an end portion 3a of the shielding foil 3 of a shielded electric cable 1, comprises a gripping device 11 for gripping the end portion la, which has an opening 22, 23 for passing the cable 1 and which is rotatable about a rotation axis X passing through such opening 22, 23 to rotate the cable 1 during the cutting operation.

[0086] The gripping device 11 will be described in detail hereunder, it also being object of the present invention.

[0087] It should be noted that in a preferred embodiment, the opening 22, 23 for passing and gripping the cable 1 has a circular section, but embodiments wherein the opening 22, 23 for passing and gripping the cable has elliptical or polygonal section are not excluded.

[0088] The apparatus 10 according to the invention further comprises drive means 52, 53; M2, M3 for rotating the gripping device 11 with respect to the rotation axis X.

[0089] With reference to figures 3 and 4, the drive means can comprise at least one motorized element M2, M3, for example an electric motor or servomotor, and at least one motion transmission element 52, 53, for example at least one shaft 52, 53 which transmits rotation to the gripping device 11.

[0090] The drive means 52, 53; M2, M3 can be controlled in such a way as to operate the rotation of the gripping device 11 in clockwise and / or counterclockwise direction and in such a way as to impart and regulate the desired angular speed to the rotation device. In an embodiment, the gripping device 11 can be rotated in clockwise and / or counterclockwise direction about the rotation axis X.

[0091] The apparatus 10 according to the invention further comprises a laser source 18 for carrying out the operation of cutting the end portion 3a of the shielding foil 3.

[0092] With reference to figures 3 - 5, the laser source 18 is placed above the deviceof the gripping device 11 and is in particular positioned above the device of the gripping device 11 along a radial direction Z, but embodiments in which the laser source 18 is placed below or next to the gripping device 11 are not excluded.

[0093] The apparatus 10 further comprises movement means 19 configured for moving the laser source 18 at least along a radial direction Z with respect to the rotation axis X, to vary the distance L of the laser source 18 from the rotation axis X during the cutting operation, depending on the variation of the value of the distance D of the shielding foil 3 from the rotation axis X, such value being measured along the straight line joining the rotation axis X and the laser source 18, as shown for illustrative purposes in the schematic representation of figure 6.

[0094] The direction Z coincides typically with said straight line, which connects the rotation axis X and the laser source 18. In other words, the laser beam emitted by the laser source 18 has an axis arranged in a radial direction with respect to the rotation axis during the cutting of the shielding foil 3. The axis of the laser is thus arranged as the direction Z, i.e. as the driving direction of the laser source 18. The cutting of the shielding foil 3 is carried out by means of a laser beam, which has an axis arranged radially with respect to the rotation axis X.

[0095] It should be noted that such distance D of the shielding foil 3 from the rotation axis X, measured along the straight line joining the rotation axis X and the laser source 18, corresponds to the precise value of the radius of the cross section of the cable 1, measured at a given instant along the straight line joining the rotation axis X and the laser source 18.

[0096] Such value of the distance D of the shielding foil 3 from the rotation axis X is constant whenever the cable is a cable of coaxial type, i.e. having a circular section and constant radius, and is instead not uniform whenever the cable 1 is, for example, a cable of the bipolar type, i.e. having an elliptical section and having a major axis and a minor axis. In a possible embodiment, the movement means 19 for moving the laser source 18 comprise, for example, a vertical guide extending along the radial direction Z with respect to the rotation axis, with a motorized slide on which the laser head 18 is mounted.

[0097] As will be better explained hereunder with reference to figure 5 or 6, the laser source 18 can be moved both closer to and away from the rotation axis X, depending on the value assumed by the distance D of the shielding foil 3 from the rotation axis X, such value being measured along the straight line joining the rotation axis X and the laser source 18.

[0098] In an embodiment, the apparatus 1 comprises detecting means 60 configured for monitoring in real time the value of the distance D of the shielding foil 3 from the rotation axis X, where such value is measured along the straight line joining the rotation axis and the laser source 18 during the rotation of the cable 1.

[0099] For example, the detecting means 60 can comprise a camera and / or sensor, for example a level or position sensor.

[0100] With reference to figure 5 and 6, the movement means 19 of the laser source 18 are configured for moving the laser source 18 along the radial direction Z with respect to the rotation axis X, whenever the value of the distance D detected at a given instant ti is different from the value of the distance D detected at the previous instant to.

[0101] Specifically, with reference to figure 6, the movement means 19 of the laser source 18 are configured for moving the laser source 18 away from the rotation axis X, whenever the value of the distance D detected at an instant ti is greater than the value of the distance D detected at a previous instant to, and for moving the laser source 18 closer to the rotation axis X whenever the value of the distance D detected at an instant ti is less than the value of the distance D detected at a previous instant to.

[0102] In other words, the movement means 19 of the laser source 18 are configured for moving the laser source 18 away from the rotation axis X whenever the precise value of the radius r of the cable 1, detected at an instant ti, is greater than the precise value of the radius r of the cable 1 detected at a previous instant to, and for moving the laser source 18 closer to the rotation axis X whenever the precise value of the radius r of the cable 1, detected at an instant ti, is less than the precise value of the radius r of the cable 1 detected at a previous instant to.

[0103] In a preferred embodiment, the movement means 19 of the laser source 18 are configured for varying the distance L in such a way that the focal plane F of the laser source 18 coincides with the cut plane T, where the cut plane is identified in the plane tangent to the end portion 3a of the shielding foil 3 at the cut point of the laser beam during the rotation of the cable 1.

[0104] With reference to figures 4 and 5, the apparatus 10 comprises an air source 7 which is delivered at a temperature of between -40°C and -20°C and preferably equal to -30°C. Preferably, the air is delivered only during the cutting operation, i.e. during the step of operating the laser source 18, to cool the surface of the end portion 3a of the shielding foil 3 while cutting it.

[0105] In an embodiment shown only for illustrative purposes in figures 3 - 5, the apparatus 10 comprises removal means 8 for removing the end portion 3 a of the shielding foil 3 cut by means of the laser source 18.

[0106] With reference to figure 5, the removal means 8 can comprise a clamp 81 and / or a suctioning duct 82.

[0107] In an embodiment, the apparatus comprises a control logic unit 100 electronically connected at least to the drive means 52, 53; M2, M3 for the gripping device 11 and / or to the laser source 18, and / or to the movement means 19 for the laser source 18 and / or to the detecting means 60 for detecting the distance D of the shielding foil 3 from the rotation axis X.

[0108] In particular, the control logic unit 100 is programmed for operating the drive means 52, 53; M2, M3 for rotating the gripping device 11, in order to rotate the cable 1 during the cutting operation, and to drive the laser source 18.

[0109] Moreover, the control logic unit 100 is programmed for driving the movement means 19 for the laser source 18, depending on the value of the distance D detected of the shielding foil 3 from the rotation axis X.

[0110] In particular, the detecting means 60 are configured for detecting the precise value of the distance D of the shielding foil 3 from the rotation axis X and for sending a corresponding signal, indicative of the value of such distance D, to the control logic unit 100.

[0111] Whenever the precise value of the distance D of the shielding foil 3 from the rotation axis X, detected at the instant ti, is greater or less than the precise value of the distance D of the shielding foil 3 from the rotation axis X, detected at a previous instant to, the logic unit 100 drives the movement means 19 for the laser source 18, as described above.

[0112] A method for cutting a portion of shielding foil 3 by means of an apparatus according to the invention will be described hereunder. The method for cutting an end portion 3 a of the shielding foil 3 of a cable 1 according to the invention comprises a first step a) of inserting the end portion la of the cable 1 into the gripping device 11 for locking it in such gripping position.

[0113] The method according to the invention comprises a second step b) of determining the value of the distance D of the shielding foil 3 from the rotation axis X.

[0114] With reference to figure 6, such value of the distance D is measured along the straight line joining the rotation axis X and the laser source 18.

[0115] It should be noted that in a possible embodiment such step b) can be performed by means of the detecting means 60 configured for monitoring in real time the value of the distance D of the shielding foil 3 from the rotation axis X during the rotation of the cable 1.

[0116] The method according to the invention further comprises the step c) of operating the drive means 52, 53; M2, M3 for rotating the gripping device 11 with respect to the rotation axis X so as to rotate the cable.

[0117] Then or contemporaneously, the method comprises a step d) of driving the laser source 18 for performing the cutting of the end portion 3a of the shielding foil 3 during the rotation of the cable 1.

[0118] The laser source 18 can be regulated during the cutting operation, for example to change the power emitted.

[0119] The method according to the invention further comprises the step c) of driving the movement means 19 for moving the laser source 18 to vary the distance L of the laser source 18 from the rotation axis X during the step d) of operation of the laser source, depending on the variation of the value of the distance D of the shielding foil 3 from the rotation axis X.

[0120] In an embodiment, the step e) of driving the movement means 19 for moving the laser source 18 is performed whenever the value of the distance D, detected at a given instant ti, is different than the value of the distance D detected at the previous instant to.

[0121] More in detail, during step e), the laser source 18 is moved away from the rotation axis X whenever the value of the distance D detected at an instant ti is greater than the value of the distance D detected at a previous instant to, and the laser source 18 is moved closer to the rotation axis X whenever the value of the distance D, detected at an instant ti, is less than the value of the distance D detected at a previous instant to.

[0122] In an embodiment, in which the apparatus 1 comprises a control logic unit 100 electronically connected at least to the drive means 52, 53; M2, M3 for the gripping device 11 and / or to the laser source 18 and / or to the movement means 19 for the laser source 18 and / or to the detecting means 60, and wherein the steps b) - e) are performed at least partly performed by means of the control logic unit 100.

[0123] At the end of the cutting operation, removal means 8 are operated for removing the end portion 3a of the shielding foil 3 cut by means of the laser source 18.

[0124] As disclosed above with reference to figure 5, the removal means 8 can comprise a clamp 81 and / or a suctioning duct 82.

[0125] In particular, in a preferred embodiment, the clamp 81 equipped with appropriate gripping elements moves towards the cable 1, takes the scrap portion of the cut portion of the shielding foil 3, pulls it out from the end portion of the cable and makes it fall into a collection container, where it is then sucked out by the appropriate duct 82.

[0126] At the end of this operation, the cable gripping device 11, held in the gripping position, is rotated in the opposite direction by the same angular distance traveled during the cutting operation, de facto returning the cable 1 to its initial position, thus unwinding it.

[0127] To complete processing, the transfer device 17 grips again the cable 1 and is then only the second rotatable body 13 of the gripping device 11 is rotated with respect to the first body 12 in the opposite direction by the same angular distance traveled during the gripping operation, thus allowing the presser elements 31, 32, 33 to return to the initial position for releasing the cable 1.

[0128] As disclosed above, the apparatus 10 comprises a gripping device 11 for the cable 1.

[0129] The present invention further concerns a similar gripping device 11 which can be used in combination with the apparatus 10 according to the invention or as a gripping device 11 for a cable 1 in combination with a different apparatus for machining cable end portions belonging to the known art.

[0130] With reference to figures 8 A - 8B, 9 A - 9B, 10A - 10B, the gripping device 11 for a cable 1 according to the invention is rotatable about a rotation axis X and comprises at least one first rotatable body 12 provided with a first opening 22 for passing the cable 1 and comprising presser elements 31, 32, 33 for the cable 1, and a second rotatable body 13 provided with a second opening 23 for passing the cable 1 and comprising pushing elements 41, 42, 43 adapted for moving the presser elements 31, 32, 33 between at least one gripping position and at least one position for releasing the cable 1.

[0131] The first body 12 and the second body 13 are arranged facing one another, in such a way that the respective openings 22, 23 are aligned along the rotation axis X.

[0132] The second body 13 is rotatable about the rotation axis X with respect to the first body 12 or vice-versa, in such a way that the pushing elements 41, 42, 43 act on the gripping elements 31, 32, 33 which are moved for locking the end portion of the cable 1 in the gripping position.

[0133] In an embodiment shown for illustrative purposes in figures 8A and 8B, the gripping elements 31, 32, 33 comprise a plurality of terminals, preferably three terminals 31, 32, 33 arranged on the first body 12 along a radial direction with respect to the rotation axis X.

[0134] This way, the presser means 31, 32, 33 for the cable 1 are movable in radial direction with respect to the rotation axis X between at least one gripping position and at least one position for releasing the cable 1.

[0135] With reference to the embodiment shown in figures 8A - 8B, 9A - 9B, the pushing elements 41, 42, 43 acting on the gripping elements 31, 32, 33 comprise a plurality of protrusions, preferably three protrusions 41, 42, 43 jutting out towards the center of the second body, each shaped on the second body 13 at the inner perimeter surface, so as to have a tapered section, i.e. with a variable distance with respect to the rotation axis X, to allow an end of a respective terminal 31, 32, 33 to slide.

[0136] In an embodiment shown in figures 8A - 8B, 9A - 9B, each presser element 31, 32, 33 has an end provided with a cam 31’, 32’, 33’ which can slide along a respective protrusion having tapered section 41, 42, 43.

[0137] Thus, as disclosed above, the second body 13 is rotatable about the rotation axis X with respect to the first body 12 or vice-versa, in such a way that the pushing elements 41, 42, 43 act on the gripping elements 31, 32, 33 which are moved in radial direction with respect to the rotation axis X for locking the end portion of the cable 1 in the gripping position: the pushing action on the terminals 31, 32, 33 is generated by the rotation of the second body 13 which, by rotating, imparts the sliding of the cams 31’, 32’, 33’ of the terminals 31, 32, 33 along the tapered protrusions of the pushing elements 41, 42, 43 jutting out towards the center of the second body 13.

[0138] It should be noted that in such embodiment, each presser means 31, 32, 33 is provided with an elastic return element 31”, 32”, 33” which allows the return of the presser means 31, 32, 33 to the position for releasing the cable 1.

[0139] In an alternative embodiment shown in figures 10A - 10B, the pushing elements 41, 42, 43 acting on the gripping elements 31, 32, 33 comprise a plurality of guides, preferably three guides 41, 42, 43 formed on the surface of the second body 13 and each shaped on the second body 13 to allow an end of a respective terminal 31, 32, 33 to slide.

[0140] Also in the embodiment shown in figures 10A - 10B, each presser element 31, 32, 33 has an end provided with a cam 31’, 32’, 33’ which can slide along a respective guide 41, 42, 43 formed on the second body 13.

[0141] Thus, as disclosed above, the second body 13 is rotatable about the rotation axis X with respect to the first body 12 or vice-versa, in such a way that the pushing elements 41, 42, 43 act on the gripping elements 31, 32, 33 which are moved in radial direction with respect to the rotation axis X for locking the end portion of the cable 1 in the gripping position: the pushing action on the terminals 31, 32, 33 is generated by the rotation of the second body 13 which, by rotating, imparts the sliding of the cams 31’, 32’, 33’ of the terminals 31, 32, 33 along the shaped guides of the pushing elements 41, 42, 43.

[0142] By reversing the rotation direction of the second body 13, the cams 31’, 32’, 33’ of the terminals 31, 32, 33 slide along the shaped guides of the pushing elements 41, 42, 43 in the opposite direction, thus bringing the device 11 back to the position for releasing the cable 1.

[0143] In an embodiment, the first and second bodies 12, 13 are further rotatable integrally about the rotation axis X to rotate the end portion of the cable 1.

[0144] In this regard, the device 11 comprises first operating means 52 for the first rotatable body 12 and second operating means 53 for the second rotatable body 13, which can

Claims

be operated independently or contemporaneously.It should be noted that by operating only the first operating means 52 for rotating the first rotatable body 12, the cable is gripped, since the second body 13 rotates with respect to the second body 12, as described above, for moving the presser means 31, 32, 33 towards the cable gripping position.By contemporaneously operating the first and second operating means 52, 53, the two bodies 12, 13 rotate integrally, i.e. contemporaneously, allowing the rotation of the cable 1 locked in the gripping position.In an embodiment, the first rotatable body 12 and the second rotatable body 13 comprise an outer toothed perimeter profile and the first and second operating means 52, 53 comprise a first and a second toothed shaft 52, 53, respectively.This way, when the toothed shafts 52, 53 are rotated, for example by means of respective electrical motors or servomotors, they operate the rotatable bodies 12, 13 of the gripping device 11.CLAIMS1. Apparatus (10) for cutting an end portion (3a) of the shielding foil (3) of a shielded electric cable (1), which covers at least one conductor (2, 20) provided with a covering layer (5, 50), wherein said end portion (3a) of said shielding foil (3) is exposed, said apparatus (10) comprising: a gripping device (11) for gripping said end portion (la), said device (11) comprising an opening (22, 23) for the passage of said cable (1) and being rotatable about a rotation axis (X) passing through said opening (22, 23) to rotate said cable (1) during the cutting operation; drive means (52, 53; M2, M3) for rotating said gripping device (11) with respect to said rotation axis (X); a laser source (18) for carrying out the operation of cutting said end portion (3 a) of the shielding foil (3); movement means (19) configured for moving said laser source (18) at least along a radial direction (Z) with respect to said rotation axis (X), to vary the distance (L) of said laser source (18) from said rotation axis (X) during the cutting operation depending on the variation of the value of the distance (D) of the shielding foil (3) from the rotation axis (X), such value being measured along the straight line joining said rotation axis (X) and said laser source (18).

2. Apparatus (10) according to claim 1, wherein said radial direction Z coincides with the axis of the laser beam which, in use condition, is emitted by the laser source (18).

3. Apparatus (10) according to claim 1 or 2, which comprises detecting means (60) configured for monitoring in real time the value of said distance (D) of the shielding foil (3) from the rotation axis (X), which value is measured along the straight line joining said rotation axis (X) and said laser source (18) during the rotation of said cable (1).

4. Apparatus (10) according to claim 1, 2 or 3, wherein said movement means (19) of the laser source (18) are configured for moving said laser source (18) along said radial direction (Z) with respect to said rotation axis (X), whenever said value of the distance (D) detected at a given instant (tl) is different from the value ofthe distance (D) detected at a previous instant (tO).

5. Apparatus (10) according to one of the preceding claims, wherein said movement means (19) are configured for moving said laser source (18) away from said rotation axis (X), whenever the value of said distance (D) detected at an instant (tl) is greater than the value of said distance (D) detected at a previous instant (tO), and for moving said laser source (18) closer to said rotation axis (X) whenever the value of said distance (D), detected at an instant (tl), is less than the value of said distance (D) detected at a previous instant (tO).

6. Apparatus (10) according to one of the preceding claims, wherein said movement means (19) for moving said laser source (18) are configured for varying said distance (L) in such a way that the focal plane (F) of said laser source (18) coincides with the cut plane (T) tangent to said end portion (3 a) at the cut point of the laser beam during the rotation of said cable (1).

7. Apparatus (10) according to one of the preceding claims, comprising an air source (7) which delivers air at a temperature of between -40°C and -20°C and preferably equal to -30°C.

8. Apparatus (10) according to one of the preceding claims, comprising removal means (8) for removing said end portion (3a) of said shielding foil (3) cut by means of said laser source (18).

9. Apparatus (10) according to one of the preceding claims, which comprises a control logic unit (100) electronically connected at least to said drive means (52, 53; M2, M3) for said gripping device (11) and / or to said laser source (18) and / or to said movement means (19) for said laser source (18) and / or to said detecting means (60).

10. Method for cutting an end portion (3a) of the shielding foil (3) of a shielded electric cable (1) by means of an apparatus (10) according to one of claims 1 - 8, wherein said shielding foil (3) covers at least one conductor (2, 20) provided with a covering layer (5, 50), wherein at least one end portion (3a) of said shielding foil (3) is exposed, said method comprising the following steps: a) inserting said end portion (la) of said cable (1) into said gripping device (11) and locking it in said gripping position;b) determining the value of the distance (D) of the shielding foil (3) from the rotation axis (X), such value being measured along the straight line joining said rotation axis (X) and said laser source (18); c) operating said drive means (52, 53; M2, M3) for rotating said gripping device (11) with respect to said rotation axis (X) to rotate said cable (1); d) driving said laser source (18) for performing the cutting of said end portion (3a) of said shielding foil (3) during the rotation of said cable (1); e) driving said movement means (19) for moving said laser source (18) so as to vary the distance (L) of said laser source (18) from said rotation axis (X) during said step d) depending on the variation of the value of said distance (D) of the shielding foil (3) from the rotation axis (X).

11. Method according to claim 10, wherein, in said step d), the axis of the laser beam is radial with respect to the rotation axis (X).

12. Method according to claim 10 or 11, wherein, in step e), the laser source is moved along the axis of the laser beam.

13. Method according to one of claims 10 - 12, wherein said step b) is performed by means of detecting means (60) configured for monitoring in real time said value of said distance (D) of the shielding foil (3) from the rotation axis (X) during the rotation of said cable (1).

14. Method according to one of claims 10 - 13, wherein said step e) is performed whenever said value of the distance (D) detected at a given instant (tl) is different from the value of the distance (D) detected at a previous instant (tO).

15. Method according to one of claims 10 - 14, wherein, in said step e), said laser source (18) is moved away from said rotation axis (X) whenever the value of said distance (D) detected at an instant (tl) is greater than the value of said distance (D) detected at a previous instant (tO), and said laser source (18) is moved closer to said rotation axis (X) whenever the value of said distance (D) detected at an instant (tl) is less than the value of said distance (D) detected at a previous instant (tO).

16. Method according to one of claims 10 - 15, wherein said apparatus (10) comprises a control logic unit (100) electronically connected at least to said drive means (52, 53; M2, M3) for driving said gripping device (11) and / or to said lasersource (18) and / or to said movement means (19) for said laser source (18) and / or to said detecting means (60), and wherein said steps b) - e) are performed at least partly by means of said control unit logic (100).

17. Gripping device (11) for gripping a cable (1) rotatable about a rotation axis (X), comprising at least one first rotatable body (12) provided with a first opening (22) for the passage of said cable (1) and comprising presser elements (31, 32, 33) for pressing said cable (1), and a second rotatable body (13) provided with a second opening (23) for the passage of said cable (1), said second body (13) having pushing elements ( 41, 42, 43) adapted for moving said presser elements (31, 32, 33) between at least one gripping position and at least one position for releasing said cable (1), wherein said first body (12) and said second body (13) are arranged facing one another, in such a way that the respective openings (22, 23) are aligned along said rotation axis (X), and wherein said second body (13) is rotatable about said rotation axis (X) with respect to said first body (12) or vice-versa, in such a way that said pushing elements (41, 42, 43) act on said gripping elements (31, 32, 33) which are moved for locking said end portion of said cable (1) in said gripping position.

18. Gripping device (11) according to claim 17, wherein said presser means (31, 32, 33) for said cable (1) are movable, in radial direction with respect to said rotation axis (X), between at least one gripping position and at least one position for releasing said cable (1).

19. Gripping device (11) according to claim 17 or 18, wherein said first and said second bodies (12, 13) are integrally rotatable about said rotation axis (X) to rotate said end portion (la) of said cable (1).

20. Gripping device (11) according to one of claims 17 - 19, which comprises first operating means (52) for said first rotatable body (12) and second operating means (53) for said second rotatable body (13), which can be operated independently or contemporaneously.

21. Gripping device (11) according to claim 20, wherein said first rotatablebody (12) and said second rotatable body (13) comprise a toothed perimeter profile and said first and second operating means (52, 53) comprise a first and a second toothed shaft (52, 53), respectively.

22. Gripping device (11) according to one of claims 17 - 21, wherein the pushing elements (41, 42, 43) acting on the gripping elements (31, 32, 33) comprise a plurality of protrusions, preferably three protrusions (41, 42, 43) jutting out towards the center of the second body, each presser means (31, 32, 33) has an end portion provided with a cam (31’, 32’, 33’), which can slide along a respective protrusion (41, 42, 43).

23. Apparatus (10) for cutting an end portion (3a) of the shielding foil (3) of a shielded electric cable (1) according to one of claims 1 - 9, comprising a gripping device (11) according to one of claims 17 - 22.

Images