FR2559613A1 - Electrical cable for carrying very high currents at low voltages and process for manufacturing such a cable - Google Patents

Abstract

The subject of the present invention is an electrical cable 1 for carrying very high currents at low voltage, especially a welding cable, comprising at least one multistrand conductor 2 and an external sheath 4, a circulation of water being provided inside the cable, characterised in that at least one multistrand conductor 2 is covered with a perforated jacket 3 permitting the circulation of water. The subject is also a process for manufacturing such a cable. Application to welding cables used in robotised welding machines.

Description

Electric cable for transporting very high currents at low voltages, and method of manufacturing such a cable
The present invention relates to an electric cable for transporting high currents at low voltages, in particular a welding cable.

 It also relates to a method of manufacturing such a cable.

 Electric cables transmitting high currents at low voltages, in particular welding cables, generally consist of one or more conductors each comprising a multitude of elementary strands covered by an outer sheath.

 bend this sheath and the conductor (s) remain channels, called * cooling, which allow water circulation necessary for cooling as cables.

 i.ais as and when these cables are used, there appears to be an abrasion of the elementary strands due to the electrodynamic vibrations and to the mechanical forces which cause an obstruction of the cooling channels. Some cables include polyester or polypropylene braids, between the conductor (s) and the outer sheath, which increase the risk of obstruction of the cooling channels.

 The object of the present invention is to significantly increase the life of the targets by reducing the breakage of elementary strands by better protection of the conductor (s) using an openwork envelope.

 The present invention relates to an electric cable for the transport of very high currents at low voltage, in particular a welding cable, comprising at least one multi-strand conductor and an outer sheath, a circulation of water being ensured inside the cables characterized in that at least one multi-strand conductor is covered with an openwork envelope allowing the circu lotion of esu.

 Advantageously, the perforated envelope consists of two layers integral with one another, each layer consisting of at least one strip.

 According to a first embodiment, one layer consists of at least one helical band and the other layer consists of at least one longitudinal layer.

 According to another embodiment, the two layers consist of helical bands.

 The present invention also relates to a method of manufacturing such a cable, consisting in covering at least one multi-strand conductor with an external sheath allowing water circulation, characterized in that, before the sheath is laid around the or conductors, a conductor is introduced separately into the center of an extruder, two layers of material integral with one another are extruded onto this conductor, an inner layer using a punch and an outer layer using a sector.

 Advantageously, a layer is produced using a rotating punch or a rotating die and a longitudinal layer using a punch or a fixed die.

 It is described below by way of example and with reference to the accompanying drawings, two electric cables according to the invention, as well as a device for manufacturing an openwork sheath to constitute such cables.

 FIG. 1 represents an electric cable according to the invention, comprising a single multi-strand conductor.

 FIG. 2 represents an electric cable according to the invention comprising three multi-strand conductors.

 FIG. 3 represents a device for manufacturing an openwork envelope for constituting electric cables according to the invention.

 In Figure 1, there is shown a cable 1 having a single stranded conductor 2, an openwork envelope 3 and an outer sheath 4. The envelope 3 comprises two separate layers but nevertheless integral with each other, an inner layer 5 in contact with the conductor 2, an external layer 7 in contact or not with the external sheath 4.

 The inner layer 5 consists of several helical bands 6 and the outer layer 7 consists of several longitudinal bands 8 which connect the helical bands 6 together.

This envelope 4 is perforated to allow the circulation of water along the cable 1, the water being in contact with the conductor 2 in the spaces left free by the helical bands 6.

 In FIG. 2, a cable 10 is shown comprising three multi-strand conductors 12, each conductor being covered by an openwork envelope 13, identical to the envelope 3 in FIG. 1. These three conductors provided with an envelope are placed in a external sheath 14 allowing water circulation. This sheath can, of course, receive only two multi-strand conductors, or four and more.

 In these two Figures 1 and 2, the envelope provides electrical insulation very wing voltage and mechanical protection of the elementary strands.

 The insulating envelope can, of course, include an outer layer 7 made up of helical bands in the opposite direction to the helical bands of the inner layer 5, or the inner layer 5 can be made up of longitudinal bands and the outer layer 7 made of helical bands.

 The number of bands for each layer is of course any number.

 In FIG. 3, there is shown a device for manufacturing a sheathed envelope for constituting electric cables according to the invention.

 A manufacturing device 20, such as an extruder, comprises a central body 21 provided with a filling funnel 22 of thermoplastic or elastomeric materials. A heating resistor 23, surrounding the funnel 22, keeps the material at its melting temperature.

 This central body 21 also includes a head 24 screwed to one end thereof and provided with another heating resistor 25.

 Fn ee sissairé the te is supported on a wedge 26. This head has a fixed die 27 which will be described in Figures 4 and 5.

 A cylindrical part 28 is held in abutment on a shoulder 29 of the central body 21, and this part 28 is fixed by three screws 30 distributed circumferentially at 1200 (a single screw is shown in broken lines).

 In this part 28 is introduced a sleeve 31 adjustable longitudinally by means of several screws 32 distributed circumferentially and locked by means of three screws 33 also distributed at 1200 (a single screw being shown).

 This bushing 31 supports two bearings 34, 35 and a fixed stop 36. A hollow shaft 37, into which a punch 38 is screwed, rotates on the two bearings 34, 35 and is supported on the punch side on the fixed stop 36 and the on the other side on a thrust bearing 39 by means of "Belleville" washers 40 and a nut 41. This shaft is driven in rotation by a motor 42 by means of a toothed pulley 43 coupling a pinion 44 of the motor 42 and a pinion 45 connected to the shaft 37 by a threaded bush 46. This device therefore comprises a material supply circuit constituted by the funnel 22, a circular groove and channels 50 distributed circumferentially between the body 21 and piece 28 from the groove to the level of the die-punch assembly.

 Figures 4 and 5 show the fixed die 27 in more detail. This die has grooves 27 ′, and to each groove 27 ′ corresponds a longitudinal strip 8 of the outer layer 7 of each envelope 3 or 13.

 Figures 6 and 7 show the rotary punch 38 in more detail. This punch has grooves-38 ', and each groove 38' corresponds to a helical strip 6 of the inner layer 5 of each envelope 3 or 13.

 An extrusion operation is carried out as follows: a multi-strand conductor 2 or 12 is introduced into the hollow shaft 37 and passes through the punch 38. This punch and this shaft are rotated by means of the motor 42. The material thermosplastic or elastomer is introduced into the funnel 22 and it follows the channels 50 then pass between the die and the punch to cover the conductor 2 or 12 and constitute an openwork envelope 3 or 13.

 By turning, the punch produces the helical bands 6 of the inner layer 5 and the fixed die produces the longitudinal bands 8 of the outer layer 7. These two layers 5 and 7 are of course integral because the material is still molten at the die and the punch.

 Without departing from the scope of the invention, another manufacturing device may include a rotating die driven by known means to form an outer layer comprising helical bands.

Claims (6)

1 / Electric cable (1, 10) for transporting very high currents at low voltage, in particular welding cable, comprising at least one multi-strand conductor (2, 12) and an outer sheath (4, 14), a circulation of water being provided inside the cable, characterized in that at least one multi-strand conductor (2, 12) is covered with an openwork envelope (3, 13) allowing # the circulation of water. 2 / electric cable according to claim 1, characterized in that the perforated envelope consists of two layers (5, 7) integral with each other, each layer (5, 7) consisting of at least one strip (6, 8). 3 / Electric cable according to at least one of claims 1 to 2, characterized in that a layer (5) consists of at least one helical strip # dale (6) and the other layer (7) consists at least one longitudinal strip (8). 4 / Electric cable according to one of claims 1 to 2, characterized in that the two layers consist of helical bands.  5 / A method of manufacturing an electric cable according to at least one of claims 1 to 4, comprising covering at least one multi-strand conductor (2) with an outer sheath (4) allowing water circulation, characterized in that, before laying the sheath around the conductor (s), a conductor (2) is introduced separately into the center of an extruder (20), two layers of material integral with each other are extruded on this conductor , an inner layer using a punch and an outer layer using a die. 6 / A manufacturing method according to claim 5, characterized in that a helical layer is produced using a rotary punch or a rotating die and a longitudinal layer using a punch or d '' a fixed sector.