CH677573B5 - - Google Patents

Abstract

Continuous filaments are provided with a flock coating by coating the filament with an adhesive material and passing it through a chamber in which a shower of uniformly distributed fibres envelopes the passing filaments. The fibres are displaced from one or more moving nets in contact with the contra-rotating cylindrical brushes at a level above that of the path of the filament.

Description

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Description

The present invention relates to a method of manufacturing a flocked wire, in which a central core is coated with a surface coating in the pasty state, in which this central core with its coating is subjected to an electrostatic flocking operation using textile fibers, in order to implant these fibers radially in this coating, and in which this coating is made to harden to anchor said fibers.

The invention also relates to an installation for implementing this method, this installation being intended for manufacturing a flocked wire comprising a central core and a surface coating in the hardened state, and comprising a space traversed by this core and in which reigns an electrostatic field arranged to orient and bring textile fibers radially towards this central core and its surface covering, as well as a supply device for distributing the fibers inside this space.

Finally, it relates to a flocked yarn obtained by this process.

Swiss Patent No. 560 953 describes a process of this type, in which an insulated electrical wire is produced, the insulating sheath of which consists of a layer of synthetic material and an area composed of bristles standing on the surface of the sheath. to form a hydrophilic coating based on cellulose fibers.

It has been found that the electrostatic flocking techniques currently used to produce this type of wire or electric cable do not allow a regular coating of fibers arranged radially with respect to the axis of this wire or cable to be obtained. Quite the contrary, these fibers being implanted in the sheath in all directions, and many of them are even arranged almost tan-gentially with respect to the outer surface of this sheath.

The main reason why these fibers are randomly implanted is that they fall irregularly into the flock hopper and, consequently, settle in such a way that their orientation as well as their density are relatively irregular on the surface of the sheath. One of the drawbacks which results from this structure is that these fibers take on the appearance of real small thorns which make this electric wire unpleasant to the touch.

The present invention proposes to overcome this drawback by producing a flocked yarn as mentioned previously comprising a coating of textile fibers implanted in the surface coating, which is pleasant to the touch, thanks to a regular arrangement of these fibers giving this coating the appearance of a particularly soft velvet.

In addition, for certain applications where it is sought to obtain a zone with a hydrophilic character, the effectiveness of this character is considerably increased because the apparent thickness of this zone is substantially equal to the real length of the textile fibers, practically all of them are arranged radially.

For this purpose, the method according to the invention is characterized in that during the electrostatic flocking operation, a regular and uniform rain of textile fibers is caused, in a space crossed by the central core with its coating surface, by driving at least one brush, arranged in contact with at least one sieve with longitudinal displacement, in rotation about an axis perpendicular to the displacement of the sieve and in a direction opposite to this displacement.

According to a particularly advantageous embodiment, the fibers are successively passed through at least two horizontal sieves, arranged one above the other and not causes the forced passage of these fibers through said sieves by means of two sets of rotating brushes, respectively associated with each of these sieves.

The installation according to the invention, as defined in the preamble is characterized in that said supply device comprises means for causing a regular and uniform rain of textile fibers, in said space, these means comprising at least one displacement sieve longitudinal and at least one rotary brush, driven in rotation about an axis perpendicular to the direction of movement of the screen and in a direction opposite to this movement.

According to a preferred embodiment, this device comprises two substantially horizontal sieves, which are mutually parallel and move longitudinally in opposite directions, and two series of rotary brushes, respectively associated with each of said sieves.

According to a particularly advantageous embodiment, the two screens constitute the two horizontal sections of the same flexible endless grid, stretched between a drive roller and at least one guide roller, these two sections being parallel to one another and spaced apart from each other. 'a distance greater than the diameter of said rotary brushes.

The rotary brushes of the series of brushes corresponding to the upper section are preferably offset relative to the vertical passing through the brushes of the second series of brushes corresponding to the lower section.

The flocked yarn obtained by the method according to claim 1 is characterized in that it comprises a central core coated with a surface coating in which textile fibers are anchored radially.

According to a preferred embodiment, the central core is a metal wire and the surface coating a thermoplastic synthetic material.

According to another advantageous embodiment, the central core is a flexible elongated element and the surface coating an adhesive.

The present invention will be better understood with reference to the description of an exemplary embodiment and the appended drawing in which:

Fig. 1 shows an elevational view, partially in longitudinal section, of the device according to the invention;

fig. 2 shows an elevation view, partial5

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LEMENT in cross section, of the device illustrated in FIG. 1.

fig. 3 shows a schematic view of the installation illustrated in FIG. 1 during the loading phase of this installation;

ia fig. 4 is a view similar to that of FIG. 3 illustrating this same installation during the phase of production of electric wires according to the method of the invention;

fig. 5 shows a view similar to that of the two preceding figures illustrating the installation during the emptying phase, and FIG. 6 shows a view similar to those of the previous three views illustrating the installation during its cleaning phase.

With reference to the figures, the installation described comprises a flocking tank 10 equipped at its base with an endless screw 11 intended for recovering unused textile fibers for recycling, and at its upper end with a device for 'feed 12 intended to supply the flocking tank 10 with new and / or recycled fibers.

The feed device consists of a feed hopper 13 in the form of a cylindrical silo 14 provided at its lower end with a conical tip 15 extended by a conduit 16 in which is housed a recycling lock 17, consisting of in a manner known per se by a wheel with drawers 18, and driven in rotation about a fixed axis by a drive motor 19. To this feed hopper 13 is associated in a manner known per se an air bag 53 whose the operation will be described in detail below, the assembly constituting a supply cyclone.

In the upper part of the flocking tank, there is mounted a fiber distributor 20 which consists of a double screen constituted by two sections 21 and 22 of an endless perforated band, stretched between a drive wheel 23 and two rollers 24. The drive wheel 21 is driven in continuous rotation by a drive motor 25 coupled to the drive wheel 23 via a wheel 26 and a chain or a belt 27. Both sieves are mutually parallel and move in translation in opposite directions. They have a multitude of openings to disperse the fibers in a rain as regular as possible.

In known installations, rotating brushes are arranged in contact with the upper surfaces of the fixed sieves, to sweep the fibers and push them back through the openings or perforations of these sieves. Due to the continuous friction of the brushes on the sieves, the bristles of these brushes deform and orient in the opposite direction to the direction of rotation of the brushes. As a result, they can no longer properly fulfill their function, and must be replaced. This type of installation makes it possible to generate a curtain of textile fibers whose width is very small, and which proves to be relatively ineffective in practice. In particular in these known installations, the floated wires in these known installations can only travel at very low speeds of the order of 10 to 20 meters per minute. The efficiency of the installation is therefore low and the results obtained are often poor.

In the present installation, the brushes 28, 29 are also rotary and the sieves pass continuously. The brushes 28, five in number in the embodiment shown, correspond to the upper sieve section 21. They are coupled together and to the drive wheel 30 of an electric drive motor 31 by means not shown. . The brushes 29, also five in number in this embodiment, correspond to the lower sieve section 22, are coupled together and linked to a drive wheel 32 of an electric drive motor 33. These motors drive, the ends of the axes of the rotary brushes and the means for coupling these brushes to these motors, are mounted in a cage 34 (see fig. 2) which can be adjusted in height, according to the double arrow A, relative to the flocking tank, so as to allow adjustment of the pressure exerted by the brushes on the sieves.

In normal operation, the upper screen 21 moves for example in the direction indicated by the arrow B and the corresponding rotary brushes 28 rotate in the direction of the arrow C. Similarly, the lower screen 22 moves in the direction indicated by arrow D and the corresponding brushes 29 rotate in the direction indicated by arrow E. It can be seen that at the upper surface of the screens, the bristles of the brushes move in the opposite direction to the direction of movement of the screens. As a result, the fibers are effectively swept through the sieve openings and fall, in the form of a uniform and regular rain towards a zone 35 formed between two parallel grids 36 and 37, in which there is an intense electrostatic field, and at through which passes a sheathed electrical wire 38, the sheath of which, in an insulating thermopiastic material, is in the pasty state, to allow the fibers to settle there.

Two ramps of fixed brushes called scrapers 39 and 40 are respectively provided at the ends of the upper screen sections 21 and bottom 22 to retain the fibers carried by these screen sections, and which have not passed through their openings.

In the lower part of the flocking tank 10 is mounted a hopper 41, the lower end of which is provided with a channel 42 in which the screw 11 is housed, driven in rotation by a drive motor 43. The end of this screw ends in a channel 44 which communicates, as shown in the schematic views of FIGS. 3 to 6, with the device for feeding the flocking tank. A hopper 45 containing new fibers is provided, at its base, with an endless screw 46 driven by a motor 47, to bring these new fibers into the hopper 41, above the endless screw 11.

The flocking tank 10 is advantageously equipped with a series of portholes 48, of rectangular shape, arranged on at least one of its side walls, to allow control of the progress of operations.

The different operating phases of

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the installation are illustrated diagrammatically by FIGS. 3 to 6. Fig 3 shows the installation during the loading phase. The cellulose fibers initially contained in the hopper 45 are transported by the screw 46 towards the screw 11 from where they are sucked by a fan 50 and discharged towards a conduit 51 which communicates with the feed hopper 13. This hopper of feed has a central tubular element 52 which is open at its lower end, and connected at its upper end to an air bag 53 which allows the evacuation of the air used to blow the fibers to the feed hopper 13, while by retaining these fibers and discharging them through a valve 54 which can be identical to the recycling lock 17 or be in the form of a movable valve.

A level sensor 55 makes it possible to define the height of the layer 56 of celluiose fibers on the upper sieve 21. During this phase, during which the sieves 21 and 22 are driven and the brushes 28, 29 are in rotation, some fibers pass through the openings or perforations of the screens and fall in fine rain at the base of the flocking enclosure. They are recycled using the worm 11.

Fig. 4 illustrates the production phase during which the grids 36 and 37 are energized and create an electrostatic field in the zone 35 located between these grids and crossed by the sheathed electric wire 38. The screens are driven in translation by the wheel d 'drive 23. The brushes 28 and 29 are also rotated in the direction of the arrows C and E, as mentioned above. The feed hopper 13 is supplied with new fibers and recycled fibers by the worm 11 and the fan 50 which returns these fibers through the conduit 51.

As shown schematically in the figure, the fibers are oriented radially with respect to the wire 38 and are planted in the sheath of this wire previously heated to be in a pasty state.

Fig. 5 schematically illustrates the emptying phase of the flocking tank after the manufacturing process of a coated wire as described above. The feeding of the tank is stopped. A valve 56 directs the fibers transported by the endless screw 11 and blown by the fan 50 into a bypass duct 57 which opens at the top of a recycling hopper 58, surmounted by an air bag 59. This hopper is equipped a valve 60 which pours the fibers into a fiber recovery tank 61.

The cleaning phase illustrated in fig. 6 consists in sucking, through a conduit 62, the fibers contained inside the flocking tank 10 while continuing to rotate the fan 50, the worm 11, the wheel 17, the valve 54, the screens 21 and 22 and the rotary brushes 28 and 29. To purge all of the conduits, tanks and hoppers, air is blown from the nozzles 63 while continuing to suck air loaded with residual fibers through the conduit 62. brushes are driven at a higher speed during this phase.

The installation described makes it possible to obtain, no longer narrow curtains of textile fibers falling more or less regularly, but a relatively large area in which the fibers fall regularly. Therefore, it is possible to work at high speed. The central webs with surface coating, whether made of textile material, elastomer or metal coated with synthetic material or glue or any other suitable material, pass at speeds of 80 to 100 meters per minute. Thanks to a very wide uniform distribution field, high yields are achieved, especially if several threads pass in parallel.

It is understood that the shape of the elements constituting this device, as well as their number and their arrangement could be modified as necessary without the principle and the essential characteristics of the invention being modified. Thus the number of rotary brushes as well as their shape and arrangement could be modified in order to promote a regular distribution of the fibers in the zone where the electrostatic field prevails and where the central core or the wire to be coated passes. a layer of fibers implanted radially in the adhesive layer or the synthetic sheath.

Claims (9)

Claims 1. Method for manufacturing a flocked wire, in which a central core is coated with a surface coating in the pasty state, in which this central core with its coating is subjected to an electrostatic flocking operation using textile fibers, in order to implant these fibers radially in this coating, and in which this coating is hardened to anchor said fibers therein, characterized in that during the electrostatic flocking operation, a regular and uniform rain of textile fibers is caused , in a space (35) crossed by the central core with its surface coating, driving at least one brush (28 or 29), disposed in contact with at least one sieve (21 or 22) with longitudinal displacement, in rotation according to an axis perpendicular to the movement of the screen and in a direction opposite to this movement. 2. Method according to claim 1, characterized in that one causes the successive passage of the fibers through at least two horizontal sieves (21 and 22), arranged one above the other, and in that 'causes the forced passage of these fibers through said sieves by means of two series of rotary brushes (28 and 29), respectively associated with each of these sieves. 3. Installation for implementing the method according to claim 1 or 2, for the manufacture of a flocked wire (38) comprising a central core and a surface coating in the cured state, this installation comprising a space (35) crossed by this core and in which there is an electrostatic field arranged to orient and bring textile fibers radially towards this central core and its surface covering, and a supply device for distributing the fibers inside this space, characterized in that that said supply device comprises means for causing a regular and uniform rain of textile fibers, in said space (35), these means comprising at least one ta- 5 10 15 20 25 30 35 40 45 50 55 60 65 5 7 CH677 573G A3 set (21 or 22) with longitudinal movement and at least one rotary brush (28 or 29), driven in rotation about an axis perpendicular to the direction of movement of the screen and in a direction opposite to this movement. 4. Installation according to claim 3, characterized in that it comprises two sieves (21 and 22) substantially horizontal, mutually parallel and moving iongitudinally in opposite directions, and two series of rotary brushes (28 and 29), respectively associated to each of said sieves. 5. Installation according to claim 4, characterized in that the two screens (21 and 22) constitute the two horizontal sections of the same endless flexible grid, stretched between a drive roller (23) and at least one roller. guide (24), the two sections state parallel to each other and spaced apart by a distance greater than the diameter of said rotary brushes. 6. Installation according to claim 5, characterized in that the rotary brushes (28) of the series of brushes corresponding to the upper section (21) are offset from the vertical passing through the brushes (29) of the second series of brushes corresponding to the lower section (22). 7. Flocked yarn obtained by the process according to claim 1, characterized in that it comprises a central core coated with a surface coating in which textile fibers are anchored radially. 8. Flocked wire according to claim 7, characterized in that the central core is a metal wire and the surface coating at least one thermoplastic synthetic material. 9. Flocked wire according to claim 7, characterized in that the central core is a flexible elongate element and the surface coating an adhesive. 5 10 15 20 25 30 35 40 45 50 55 60 65 6