FR2649641A1 - Extrusion die incorporating a device for forming a filamentary reinforcement within the extruded tube - Google Patents

Abstract

According to the invention, this extrusion die 10, 11 makes it possible to embed, during extrusion, in a tubular profile extruded in a single pass, a filamentary reinforcement onto two layers, a first layer of longitudinal filaments (wires, yarns) 1 and a second layer constituted by a filament 2 spirally encircling the longitudinal filaments 1, the latter being fed into the mass of extruded material via calibrated passages made radially in the die support 6 and between the two front 10 and rear 11 parts of the die, the spiroidal encircling filament 2 being delivered via a rotary filament holder 5 mounted on the front of the die support 6, with interposition of sealing rings 8 providing an air cushion (bearing), this filament 2 passing through a die nozzle 9, supported centrally by the rotary filament holder 5, which spirally delivers it onto the longitudinal filaments 1.

Description

 The present invention relates to an extrusion die incorporating a wire frame forming device internal to the extruded tube. More specifically. it relates to such a die provided with a device for distributing and drowning in the thickness of the elastomer or plastomer tube. during a single extrusion pass, a two-layer wire frame, the first layer of which consists of longitudinal wires arranged along the generatrices of the tube and which are entrained by the extruded material. and the second layer of which is in the form of a layer encircling longitudinal wires and constituted by a wire distributed in a spiral where the pitch of the turns can be dimensioned on demand as a function of the speed of extrusion of the tube and / or the speed of rotation of the distributor of the encircling wire. This die according to the invention is therefore suitable for extruding, in a single extrusion pass, a plastic or rubber tube with its wire frame incorporated in its thickness at a chosen position but preferably located at the average circumference of this thickness.

 In the current technique of manufacturing reinforced tubes of plastic or extruded rubber, the tubes are obtained after three successive operations which can be defined as follows: a first extrusion operation by which the internal tubular part or internal tube is produced . a second operation which consists in providing this internal tube with an external frame produced by taping or knitting. or braiding, and finally. a third operation in which we pass this inner tube thus reinforced into an extrusion head in order to constitute a tubular coating of determined thickness on the outside of the frame.

 It is obvious that these three successive operations are very expensive because of their duration over time and the need to use two extruders having different settings and a particular apparatus for manufacturing the armature which, in general, is very complicated and prohibits high production speeds. Consequently, the arms tubes obtained are of a high cost price and their selling price is all the more increased so that some users delay as much as possible the replacement of the armed tubes which they use and this very often to the detriment of work safety. In addition, the reinforced tubes thus manufactured often have drawbacks in that their inner tubular part is not always integral with the frame and risks inconceivable deformations with their use. for example. as a sheath or envelope for electrical targets supplied with low voltage and cooled by # an industrial water circulation.

 It is in order to make the manufacture of such reinforced tubes less expensive and to eliminate the major part of their nconadvantages of use that the applicants have designed the extrusion die which is the subject of the present invention.

 According to the invention. this extrusion die of a reinforced tube made of plastic or rubber is more particularly suitable for mounting on an extrusion head comprising an extrusion chamber with controlled veins known in the art and forming the subject of the French patent n 79.31.048. Among other things, this extrusion die incorporating a wire frame shaping device internal to the extruded tube and mounted in a die support fixed on the body of the extrusion head is remarkable by the fact that it is conical in shape and consists of two parts fixed one on the other in a fixed manner and providing between them calibrated passages communicating with radial orifices passing through the die support and where the longitudinal wires of the first layer d are engaged reinforcement of the tube during extrusion. this die support also supporting, engaged on its front part, in a rotary manner, by means of a blind bore, a thread holder. driven in rotation by a motor pinion, which distributes in a spiral a wire for encircling the longitudinal wires constituting the second armature layer, this wire holder being pressed by the bottom of its blind bore on the front face of the die support with interposition of sealing rings giving rise to an intermediate air cushion and supporting, engaged in its central bore, a die nose which is kept pressed on the front face of the front part of the die by means of a closure ring fixed on the front face of this rotary thread holder by means of threaded studs allowing the adjustment of the pressure of the die nose on the front part of the die so that the rotation of this die nose can be done without exhaust of extruded material.

 More specifically. the die support, forming between its front face and the bottom of the cylindrical blind bore of the rotary wire holder for distributing the encircling wire, an intermediate air cushion, is provided with an inlet orifice air supplying this cushion, which provides an evacuation of air, in di: ection of the external surface or "skin" of the extruded tube, by means of capillaries crossing radially the nose of the rotary die, this air intake by the capillaries allowing good, extrusion of the tube without deterioration of the "skin" thereof.

 Furthermore, the calibrated passages, formed between the two front and rear parts of the die proper and into which the longitudinal reinforcing wires slide from the outside via the radial orifices of the die support, are each made up by two semi-circular grooves located one opposite the other and made respectively in each of the two interior faces, fixed one on the other in a fixed manner. front and rear parts of the die.

 In addition, it should be noted that the front part of the die is machined so as to form longitudinal grooves, the grooves of which have a hollow bottom which is rounded longitudinally and or opens out, substantially at the level of the average circumference of the thickness of the tube, each calibrated passage for supplying the longitudinal reinforcing wires so that they are entrained by the mass of extruded material, without increasing the extrusion pressure.

 On the other hand, the rotary thread holder is provided with a single calibrated passage, extended by a passage made in the nose of the rotary die, to distribute the encircling wire in a spiral around. longitudinal wires of the first reinforcing layer, this passage in the nose of the rotary die being conformed to open out substantially at the level of the circle circumscribed by these longitudinal wires. Note that the speed of rotation of the wire holder can be changed at any time during the extrusion by acting on the rotation control constituted by the motor pinion so that a second layer of armature can be obtained 'of encirclement whose pitch between' turns' can be varied on demand.

 Furthermore, when the die according to the present invention is mounted on an extrusion head incorporating an extrusion enclosure with controlled veins.

it is also possible to extrude a tubular profile, having straight parts as well as curved parts, by slowing the supply of extrusion material in certain veins of the enclosure and at the same time slowing down the speed of supply of the wires corresponding longitudinal of the first, reinforcement layer, the surrounding wire of the latter being, therefore, distributed in the curved parts following radial turns to these curves. It is also possible to reinforce the second encircling layer in these curved parts by accelerating the speed of rotation of the wire holder and, consequently, the speed of supply of the encircling wire.

 Other characteristics of the present invention will appear from the following description of an embodiment of an extrusion die incorporating a wire frame shaping device, in accordance with the invention, given by way of non-limiting example and shown in the accompanying drawings in which: - Figure 1 is an overall perspective view, and partially in section, of the die according to the invention mounted on an extrusion head. Note that, in this figure 1 , the extruded tube is partially shown in section to see the configuration of its incorporated wire frame but that intentionally and to facilitate understanding there is shown only one of the longitudinal wires I of the first layer of armature and that the central core 16 of the extrusion head is shown in solid lines when it should be dotted in the interior of the tube.

- Figure 2 is a half cross-sectional view taken at the arrows II-II indicated in Figure t.

 As shown in these FIGS. 1 and 2, the extrusion die 10, 11, incorporating a shaping and incorporation device in the extruded tube 12, of a wire frame in two layers, a first layer of longitudinal wires 1 and a second layer consisting of an encircling wire 2 distributed in a spiral around the longitudinal wires, is mounted in a die support 6, fixed in the usual way by a flange on an extrusion head 15.

 As best seen in Figure 1. the die is of conical outer shape and consists of two parts, 10 and 11, fixed one on the other in a fixed manner, but providing between them calibrated radial passages communicating with orifices, passing radially through the die support 6, and in which the longitudinal wires 1. of the first armature layer of the tube, are engaged and circulate at the same feed speed as that of the extrusion of the tube 12. Note that the calibrated passages for the longitudinal wires I each consist of two corresponding semi-circular grooves each made respectively in the faces pressed one on the other of the two die parts 10 and 11.

 The die support 6 also supports, on its end opposite to its fixing flange on the extrusion head 15, a rotary thread holder 5 which is rotated, in the direction of the arrow F, by a motor pinion 13 and which is engaged via its blind cylindrical bore Sa on the die support 6. The rotary thread holder 5 is also provided in its central bore with a die nose 9 which is held by ~ a ring 7.This rotary thread holder is also crossed radially by an orifice, extended in the nose of the thread 9, for the passage and the spiral distribution of the encirclement wire 2, longitudinal wires 1, constituting the second layer of the reinforcement incorporated during the single pass extrusion of the extruded tube 12.

 It should be noted, as can be seen in FIG. 1. that the wire holder 5 is pressed by the bottom of its blind cylindrical bore Sa on the corresponding face of the die support 6 by means of sealing rings B which thus provide an air cushion which is supplied with air through an orifice 3 formed in the die support 6, this air cushion communicating with radial capillaries C. formed in the rotating die nose 9, so that the the evacuation of air passing through these capillaries allows good extrusion of the tube 12 without any deterioration of the outer wall or "skin" thereof.

Furthermore, it will be noted that, according to the invention, the die nose 9, supported centrally by the rotary thread holder 5, is kept pressed by its rear face on the front face of the front part 10 of the die by means of the closure ring 7 fixed on the front face of the rotary thread holder 5 by means of threaded studs. These studs are arranged so as to further allow adjustment of the pressure of the die nose on the front part 10 of the die , thanks to the fle ^. ~ on of elastic washers. so that the rotation of this nose 9, driven by the wire holder 5 and the ring 7, can be done without escaping extruded material,
On the other hand, as best seen in Figure 2, the front part 10 of the die is machined so as to form longitudinal grooves whose grooves 17 between the ribs have a rounded hollow bottom (see fig. 1) longitudinally and in which each calibrated passage for supplying a longitudinal wire 1 is shaped to open out substantially at the level of the average circumference of the thickness of the extruded tube. With this arrangement of grooves, the longitudinal wires 1 are entrained, during extrusion, by the mass of extruded material, without, however, an increase in the extrusion pressure occurring.

 From the above description. we can easily deduce that. if the speed of rotation of the wire holder 5 is varied relative to the speed of extrusion of the tube, it is possible to obtain, during extrusion, a second layer of reinforcing wire 2 whose no turns can be increased or decreased dimensionally on demand.

 Furthermore, if this die according to the present invention is mounted on an extrusion head 15 incorporating an extrusion enclosure 14 with controlled veins (as shown in FIG. 1) it is possible to extrude a tubular profile comprising parts straight and curved parts, at various angles of curvature. by slowing down the supply of extrusion materials in certain veins of the enclosure 14 chosen to correspond to the internal curvature of the curved parts, the supply of the longitudinal wires being at the same time slowed down since they are entrained by the mass of material extruded in the corresponding grooves 17 of the die, It is also possible, by increasing the speed of rotation of the thread holder 5 at the time of the extrusion of curved parts, to reinforce the second layer of reinforcement of these parts by means of the wire d 'encirclement 2 whose feeding speed is accelerated.

 It is perfectly understood that by means of this die, mounted on an extrusion head incorporating an enclosure t controlled and controlled veins as we have just said, it is possible to obtain, in a single extrusion pass, all shapes or configurations of profiles. tubular with incorporated reinforcement, such as in particular curved hoses or making various contortions, as well as pipes of the same kind for air conditioners or other apparatuses, without having recourse to additional operations of curvature t hot or similar as is currently the case the manufacturing of current technology.

Claims (7)

 1.- Extrusion die incorporating a device for distributing and drowning in the thickness of a tubular profile of elastomer or plastomer. during the extrusion thereof in a single pass, a two-layer wired reinforcement, the first layer of which is made up of longitudinal wires and the second layer of a spiral encircling wire of these longitudinal wires, this die , designed in a conical shape to be mounted at the outlet of an extrusion head. being characterized in that it consists of two parts (10,11) fixed one on the other in a fixed manner and providing between them calibrated passages communicating with radial orifices passing through the die support (6) and or are engaged the longitudinal son (1) of the first armature layer of the tube being extruded. this die support (6) also supporting. engaged on its front part, in a rotary manner, by means of a blind bore (Sa), a wire holder (5), driven in rotation by a drive roller (13), which distributes in a spiral an encircling wire ( 2) longitudinal wires (I) constituting the second reinforcing layer, this wire holder (5) being pressed by the bottom of its blind bore (5a) on the front face of the die support (6) with interposition of rings sealing (8) giving rise to an intermediate air cushion and supporting, engaged in its central bore, a die nose (9) which is kept press on the front face of the front part (10) of the die at by means of a closure ring (7) fixed on the front face of this rotary thread holder (5) by means of threaded studs and elastic washers allowing the pressure of the die nose (9) to be adjusted on the front part of the die so that the rotation of this die nose can be done without escaping material e xtruded.  2.- die according to claim 1, characterized in that the die support (6). forming between its front face and the bottom of the cylindrical blind bore (Sa) of the rotary wire holder (5) for distributing the encircling wire (2), an intermediate air cushion. is provided with an air inlet orifice (3) supplying this cushion, which provides an evacuation of air, in the direction of the external surface or "skin" of the extruded tube. by means of capillaries radially passing through the nose of the rotary die, this arrival of air by the capillaries (r) allowing good extrusion of the tube without deterioration of the "skin" of the latter.  3.- die according to claim 1, characterized in that the calibrated passages, formed between the two front and rear parts of the die itself and in which slide the longitudinal son (1) of frame from the outside by through the radial holes of the die support (6). each consist of two semicircular grooves located one opposite the other and formed respectively in each of the two interior faces, fixed one on the other in a fixed manner, front (10) and rear ( 11) of the sector.  # .- Die according to claim I. characterized in that the front part (10) of the die is machined so as to form longitudinal grooves whose grooves ~ (17) have a hollow bottom (17a} rounded longitudinally and where opens, appreciably at the level of the average circumference of the thickness of the tube, each calibrated passage for supplying the longitudinal wires (I> of reinforcement so that these are entrained by the mass of extruded material, without however increase the extrusion pressure.  5.- die according to claim 1, characterized in that the rotary thread holder (5) is provided with a single calibrated passage, extended by a passage made in the nose of the rotary die (9), to distribute the wire encirclement (2) in a spiral around the longitudinal wires of the first reinforcement layer, this passage in the nose of the rotary die (9) being shaped to open out substantially at the level of the. circle circumscribed by these longitudinal wires (1).  6.- die according to claim 1, characterized  by the fact that the speed of rotation of the thread holder (5) can  be modified at any time during extrusion by acting on  the rotation control constituted by the drive roller (13)  so we can get a second layer of reinforcement  in encircling wire whose pitch between turns may be  varied on demand.  7.- die according to claim 1, mounted on  an extrusion head incorporating an extrusion enclosure  (14) t controlled veins (known per se), characterized by  the fact that it makes it possible to extrude a tubular profile 'having straight parts as well as parts  curves, slowing the supply of extrusion material  in certain veins of the enclosure (14) and by slowing down  at the same time the wire feed speed  longitudinal (1) corresponding to the first layer of reinforcement, the encircling wire (2). of these  finding, therefore, distributes in the curved parts  following radial turns to these curves, which we can  reinforce the second encircling layer by accelerating the  speed of rotation 'of the thread holder (5) and; therefore, the  feed speed of the encircling wire (2).  8.- New industrial product, in the form of a  reinforced tubular profile comprising straight parts and  curved parts, or making various contortions, and obtained by means of a die according to claim t, characterized in that it is made in a single extrusion pass with a wire frame embedded in its thickness, substantially located t the average circumference of  the latter and comprising a first layer of longitudinal wires 1 and a second layer of wire 2 distributes in  spirals around the first layer and encircling it, the pitch of the turns being regular or varied from one part of the profile to another.