Roll-up system for pre-spun casing

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a winding system for pre-spun sheathing. STATE OF THE ART

[0002] Pre-stretched corrugated tubular conduits offer several advantages for electrical cable installation, such as faster installation and space-saving storage. Such conduits are typically available in coils with between 25m and 100m of conduit and cables arranged inside the conduit.

[0003] Such pre-wired sheaths are manufactured by extruding a plastic material. An extrusion head is positioned around one or more electrical cables and forms the sheath around the cables. The pre-wired sheath is then transferred to a winding system comprising a winding drum and an automatic cutting device to be packaged into coils. Such a winding system is for example described in the Cable Equipments document: "PREFIL-COCCI pre-wired machine", URL: https: / / www.cable-equipments.com / fr / produits-detail / 342-prefileuse-prefil-cocci.html. The production speed is high, typically up to 60m / minute.

[0004] The manufacture of pre-wired ducts presents a number of challenges. For example, the cables shrink during winding and cutting of the duct and are no longer visible from the outside. It is therefore impossible to check the presence and composition of the cables in a duct packaged in a coil.

[0005] To access the cables, manually cutting the empty portion of the sheath is slow and laborious. Cutting the empty portion by machine would interfere with the winding and cutting system and is therefore not feasible on existing equipment. STATEMENT OF THE INVENTION

[0006] An aim of the invention is to design a system and a method for winding a pre-wired sheath making it possible to avoid retraction of the cables inside the sheath.

[0007] To this end, the invention proposes a system for winding a pre-spun sheath, said sheath surrounding at least one cable, comprising a feed arm, a rotating drum for winding the pre-spun sheath fed by the feed arm in the form of a crown and a device for cutting the sheath and each cable after formation of the crown, said winding system being characterized in that it comprises a welding device comprising an ultrasonic generator, a movable part in a direction transverse to the sheath comprising a sonotrode coupled to said generator, said sonotrode being adapted to convert the energy of said ultrasound into melting energy of the sheath, the movable part being configured to bring the sonotrode into contact with the interior of the sheath to weld a portion of the sheath to a portion of at least one of said cables.

[0008] Since each cable is welded to the sheath, it is prevented from shrinking. Therefore, after cutting, each cable is visible and accessible at the end of the sheath.

[0009] Advantageously, the system comprises a support surface for the sheath facing the welding device. Preferably, the movable part is movable between an open position adapted to allow the passage of the sheath between the support surface and the sonotrode and a welding position in which the sheath is pinched between the support surface and the sonotrode. The movable part comprises a pneumatic slide.

[0010] The cutting device is arranged to cut the sheath on the outer side of the welded portion in the direction of winding of the sheath.

[0011] The system comprises a control unit configured to detect that a determined length of pre-spun sheath has been wound onto the drum, immobilize the drum, stop the supply of the sheath and trigger the welding device. The system further comprises a device adapted to determine the length of the sheath wound onto the drum.

[0012] The control unit is configured to activate the cutting system when the weld is completed.

[0013] Another object of the invention relates to an installation for manufacturing a pre-spun sheath, comprising an extrusion line adapted to form a sheath around at least one cable and a winding system.

[0014] The invention also relates to a method of winding a pre-spun sheath surrounding at least one cable, comprising the following steps: providing a system as described above, winding said sheath through the rotating drum to form a crown, stopping the rotation of said drum and the feeding of the sheath, fixing by ultrasonic welding a portion of the sheath to a portion of at least one cable, cutting the sheath and the cables by the cutting device.

[0015] Advantageously, the portion of the cable fixed to the sheath by welding is a portion of electrical insulation. Preferably, the cut is made between the welded portion of the sheath and the crown wound on the drum. BRIEF DESCRIPTION OF THE FIGURES

[0016] Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings, in which: There figure 1 illustrates a pre-wired sheath with and a sheath without cables. The figure 2is a schematic view of a winding system according to the invention. The figure 3 is a schematic view of a pre-wired conduit feed arm. The figure 4 is a schematic view of the welding system. The Figure 5 illustrates a pre-wired sheath having a weld with electrical cables. DETAILED DESCRIPTION OF EMBODIMENTS

[0017] A pre-wired sheath 10 is typically a corrugated plastic sheath having one or more electrical wires 12 as illustrated in the figure 1 . Said wires 12 may or may not have electrical insulation. The pre-wired sheaths are packaged in coils in a winding system as illustrated in the figure 2 .

[0018] Said winding system mainly comprises a rotating drum 30, a sheath feeding arm 20, and a control system.

[0019] The rotating drum 30 is arranged to wind a sheath in the form of a crown. Said drum comprises a system for fixing the portion of the sheath which is intended to be inside the crown, a core 31 capable of receiving the sheath in wound form, and at least one flange 32 arranged to laterally delimit the turns of the sheath wound on the core 31. The core 31 may be a set of rigid parallel bars forming a frame on which the sheath is wound. Typically, the core 31 receives a sheath with a final length of between 25 and 100 m during each winding cycle. The fixing system is typically a pneumatic clamp arranged to block the end of the sheath inside the crown.

[0020] The drum further comprises a motor or other system arranged to drive the core 31 in rotation, and a speed management system depending on the speed of arrival of the pre-spun sheath in the winding system. By way of illustrative and non-limiting example, the rotation speed is between 0 and 200 rpm. The drum further comprises a brake arranged to stop the rotation between the winding cycles and in the event of an emergency. The rotation is interrupted for a certain duration, for example approximately 1 second, after each winding cycle, to allow the withdrawal of the formed crown and the release of the core 31 for the winding of another crown.

[0021] The duct feed arm 20 is illustrated in detail in the figure 3The feed arm comprises a coding wheel 21 driven in rotation by means of the sheath 10. The coding wheel 21 is equipped with a system for counting the number of rotations, from which the length of the wound sheath can be calculated. Said counting system transmits data to the control system in order to determine the end of the winding cycle when the final length of the sheath for packaging a crown is reached.

[0022] The feed arm 20 further comprises a puppet 22 capable of controlling the speed of winding of the pre-spun sheath as a function of its current tension.

[0023] The feed arm further comprises a cutting system 23 adapted to simultaneously cut the sheath and the cables inside the sheath when the winding of a crown is finished.

[0024] In reference to the figure 4, the feed arm comprises an ultrasonic welding system 24 adapted to weld a portion of the sheath to a portion of at least one of the cables included in the pre-spun sheath. An ultrasonic welding system typically comprises an electrical signal generator (not shown) and a piezoelectric system capable of transforming the electrical signals emitted by the generator into ultrasonic waves. The system further comprises a sonotrode 27 transforming the ultrasonic waves into welding energy. In an illustrative and non-limiting manner, the sonotrode 27 may be rectangular, round or oval.

[0025] For ultrasonic welding, said sonotrode 27 is brought into contact with the inside of the sheath. For this purpose, the sonotrode 27 passes through the sheath (the ultrasound melts the material of the sheath which can then be perforated by the sonotrode 27) until it comes into contact with the wires and the inside surface of the sheath opposite the opening previously made in the sheath.

[0026] Advantageously, the sonotrode 27 is arranged on a movable part which may be a pneumatic slide. The movable part is movable relative to a fixed part of the welding system arranged in the arm for feeding the pre-spun sheath. The movement of the movable part relative to the fixed part is transverse to the direction of feeding of the pre-spun sheath. Said movable part is capable of applying the sonotrode 27 to the sheath to be welded during ultrasonic welding, and of removing the sonotrode 27 from the sheath when the welding is completed. When the sonotrode 27 is applied to the sheath, a bearing surface 25 receives the area of the sheath in contact with the sonotrode 27 to prevent deformation of the sheath during welding.

[0027] In a purely illustrative and non-limiting example, a welding system 24 used for a pre-spun sheath comprising three wires, having an outer diameter of 16 mm, operates at a power of 111 W and a frequency of 35295 Hz and an energy of 93.5 Ws. The duration of the welding process is, by way of purely illustrative and non-limiting example, approximately one second.

[0028] In one embodiment and for purely illustrative and non-limiting purposes, the weld has a length of 12 mm in the direction of the length of the sheath.

[0029] Preferably, the winder control system can be used to control the sonotrode 27 and the moving part.

[0030] The control system includes a computer configured to determine the length of the sheath already wound from the measurements of the encoder wheel, and to control the movement of the sonotrode 27, the execution of the ultrasonic welding, and the cutting of the sheath when the intended length is reached.

[0031] In a pre-spun sheath manufacturing facility, such a winding system is typically installed downstream of an extrusion line suitable for forming a sheath around at least one cable.

[0032] The 24 ultrasonic welding system can be installed on an existing pre-spun duct winding device. The system also allows the space requirements and automation of an existing winding device to be taken into account. In the case of a winding system equipped with a 27 sonotrode during its construction, fewer space constraints need to be taken into account.

[0033] The method for winding a pre-spun sheath in a system according to the invention will now be described. The sheath is fixed on the core 31 of the drum 30 and the drum 30 is rotated, winding the pre-spun sheath in the form of a crown. During this phase, the movable part is in an open position allowing the passage of the sheath between the bearing surface and the sonotrode. When the desired length of sheath is wound on the drum, the rotation of the drum is stopped. Then, the movable part moves the sonotrode 27 in the direction of the sheath and until reaching a welding position in which the sonotrode 27 is applied to the portion of the sheath to be welded. Simultaneously, the sheath is held by the bearing surface arranged on the side of the portion to be welded opposite the movable part comprising the sonotrode 27.

[0034] The generator sends an electrical signal exciting the piezoelectric system, and the sonotrode 27 begins to weld the sheath. The sheath melts and the sonotrode 27 advances gradually towards the contact surface. The molten sheath fuses with one or more cables included within the sheath, which creates a mechanical bond between the sheath and said cable(s). In some embodiments, the sheath fuses with a portion of the insulation of one or more cables, which may also be melted by the energy provided by the sonotrode 27. Alternatively, the sheath may fuse with a portion of a cable without insulation.

[0035] When the programmed welding time is reached, the moving part is retracted and retracts the welding device to release the sheath. The welding time is typically about 1 second.

[0036] Simultaneously, the cutting device 23 cuts the pre-spun sheath comprising the cables between the welded portion 15 of the sheath and the crown wound on the drum.

[0037] Ultrasonic welding is performed during the time the drum is stopped rotating without extending the time of the winding cycle and the stopping of the rotation.

[0038] The coil is then removed from the drum and the portion of the sheath containing the weld is fixed to the drum. The drum is rotated to wind a new coil of sheath arriving from the feed arm. In the portion inside the coil that is being formed, the cables are fixed to the sheath by means of the weld. The cables cannot therefore shrink inside the sheath during and after the winding process.

[0039] There Figure 5illustrates a pre-wired sheath 10 comprising insulated electrical wires 12. It is observed, through an opening 17 formed by the application of the sonotrode 27 on the sheath 10, that the portion 15 of the sheath opposite said opening is welded to the electrical insulation of the cables 12. The cables 12 cannot therefore shrink in the sheath 10 and are visible from the outside. For the final installation of the pre-wired sheath, the end of the sheath comprising the portion 15 is cut, the welding and the drilling therefore do not impose any constraints in the electrical installation of the cables 12. Such a portion 15 of sheath is arranged inside each crown packaged in a winding system according to the invention.

Claims

1. A system for winding a pre-threaded sheath, said sheath surrounding at least one cable, comprising a feed arm, a rotating drum for winding the pre-threaded sheath fed by the feed arm into a coil and a device (23) for cutting the sheath and each cable after the coil has been formed, said winding system being characterized in that it comprises a welding device (24) comprising an ultrasound generator and a part movable in a direction transverse to the sheath comprising a sonotrode (27) coupled to said generator, said sonotrode being adapted to convert the energy of said ultrasound into sheath melting energy, the movable part being configured to bring the sonotrode into contact with the inside of the sheath to weld a portion of the sheath to a portion of at least one of said cables .

2. System according to claim 1, comprising a sheath bearing surface facing the welding device (24).

3. System according to claim 2, wherein the movable part is displaceable between an open position adapted to allow passage of the sheath between the bearing surface and the sonotrode and a welding position in which the sheath is clamped between the bearing surface and the sonotrode.

4. System according to one of claims 1 to 3, in which the moving part comprises a pneumatic slide.

5. System according to one of the preceding claims, in which the cutting device (23) is arranged to cut the sheath on the outer side of the welded portion in the direction of sheath winding.

6. System according to one of the preceding claims, comprising a control unit configured to: detect that a given length of pre-wound sheath has been wound onto the drum, immobilize the drum, stop the sheath feed and trigger the welding device (24).

7. System according to claim 6, comprising a device adapted to determine the length of the sheath wound on the drum.

8. A system according to claim 7, in which the control unit is configured to activate the cutting system when welding is complete.

9. Installation for manufacturing a pre-threaded sheath, comprising an extrusion line adapted to form a sheath around at least one cable and a system for winding according to one of claims 1 to 8.

10. Method of winding a pre-threaded sheath surrounding at least one cable, comprising the following steps: • supplying of a system according to one of claims 1 to 8, • winding said sheath via the rotating drum to form a coil, • stopping the rotation of the drum and the sheath feed, • ultrasonic welding of a portion of the sheath to a portion of at least one cable, • cutting of the sheath and the cables by the cutting device (23).

11. Process according to claim 10 in which the portion of the cable attached to the sheath by the welding is an electrically insulating portion.

12. Process according to one of claims 10 to 11 in which the cutting is carried out between the welded portion of the sheath and the coil wound on the drum.