FI62813C - FREQUENCY REQUIREMENT FOR FRAMSTERING AV FIBER FRAME AND UTDRAGBART MATERIAL - Google Patents

Description

E3F * 1 rB] ^ 'ANNOUNCEMENT A 0 η. τ ^ RHjft lJ 1 'utlAggningsskrift ο ^ οιό C (45) Patsntti ayönnelty 10 03 1983 ^ ^ pi) κν.Ηι.3 / ΐικ.α3 C 03 B 37/06 FINLAND — FINLAND (21) Ncw «niMi ^ ~ NtwtMM «iii | 7818U1 (22) HalMmUpIhit — AmSknlniidaf 0Ö.06.7Ö '' (23) Starting dates — GlMghaeadtg 08.06.78 (41) Interpreters (ulkMcil - MMt offantHf 21 + .02.80

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Patent · och reglsterstyreisan '' AmMcm utia «d och ucUkrifcM pubiicand 30.11.82 p2) (33) (31) ^» «y utuelkuui — Bujlrd prtorlm 23.08.78

France-France (FR) 7725692 (71) Saint-Gobain Industries, 62, Bd Victor-Hugo, 92209 Neuilly sur Seine, France-France (FR) (72) Marcel Levecque, Saint-Gratien, Jean A. Battigelli, Rantigny,

Dominique Plantard, Rantigny, France-France (FR) (7 * 0 Berggren Oy Ab (5l) Method and apparatus for making fibers from a stretchable material -Forfarande och anordning för framställning av fibrer frän ett utdrag-Bart material

The invention relates to a method and an apparatus for producing fibers from a stretchable material and relates in particular to the stretching of thermoplastic materials, in particular mineral substances such as glass and the like, which have been brought into a molten state by heating. The invention also relates to the defibering of certain organic substances such as polystyrene, polypropylene, polycarbonates and polyamides; however, since the device is of particular interest in the stretching of glass and the like thermoplastics, this explanation is directed, for example, to the stretching of glass.

Some methods using eddy currents to produce fibers by stretching molten glass are already known.

Specifically, French Patent 2,223,318 describes the formation of counter-rotating pairs of vortices in an interaction zone obtained by passing a gas jet, called a secondary or carrier jet, to penetrate a larger main gas stream therein, whereby the thread melts the glass. Multiple showers can be connected to the same main stream.

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In addition, Finnish. pat. No. 61676 (Pat. No. 773788) is described as primary stretching in two stages, the first stage taking place in each secondary jet, while the second stage takes place in the corresponding interaction zones of the main stream. In said application, the secondary jets leave a distance from the main stream and the supply point of the material to be stretched, and the jets are disturbed by a deflector system.

More specifically, the secondary jets leaving the array of nozzles are directed toward the surface of the deflector, which causes their direction change and the direction jets to flow in the direction of the main current. Upon penetrating into the mainstream, these deflected jets develop interaction zones in the mainstream with vortex pairs in which stretching occurs as described above. In addition, the jets are positioned relative to the deflector in such a way that, when they collide with the surface of the deflector, the jets spread to the sides and the jets are further so close to each other that neighboring jets come into contact with each other close to the free edge of the deflector. This change in the direction of the jets and the collision with each other causes the formation of vortex pairs and low-pressure zones, which are located immediately downstream of the edge of the deflector and into which ambient gases or air are entrained.

The vortices are formed at the edges of each jet and thus surround every low-pressure zone where the flow is virtually laminar. The molten glass fibers are fed into these flow zones of the laminar, allowing the supply of glass fibers to this system to be stabilized. Each glass fiber is then carried by the flow of each jet and transported to the corresponding interaction zone formed by the penetration of the jet into the main stream in which the interaction zone the glass fiber becomes stretched.

According to the present invention, as in Finnish pat. No. 61676 (Pat. No. 773788), by causing the jets to penetrate the main stream and stretching the glass strands in these zones, but on the one hand the jets are developed differently and on the other hand the molten glass strands are fed to these jets at different points.

According to the present invention, a plurality of adjacent gas jets are developed at a distance from each other and against a convex guide surface, 6281 3 3 that the direction of the gas jets and their induced currents is changed by causing them to flow along said convex guide surface. zones of laminar flow, and that the strands of stretchable material are fed between gas jets, into laminar flow zones, whereby said strands are drawn into and stretched in the flow of gas jets, and that the direction is changed so that the kinetic energy of each gas jet per unit volume is greater than that of the main stream so that the gas jets can penetrate and interact with it; zones into which the partially stretched strands of material are fed for additional stretching.

The cross-section of each jet is larger in the direction of the concave surface than in the direction perpendicular to it, so that the jets flow along this surface in accordance with its curvature. This change in the direction of the jet, which develops as the jet follows the curved surface, is known as the Coanda phenomenon. A change of direction along a concave surface causes the development of two vortices rotating in opposite directions in the flow of each jet. The directions of rotation of the vortices and the distances of the adjacent jets are such that the absorbed gases travel, upon contact with the surface of the control members, to the spaces adjacent to the jets. The flow of ambient gas or air absorbed into each jet is almost laminar at the guide surface, and the molten glass fibers are fed into each laminar stream between two adjacent jets. This feeding of glass into the flow zones of the laminar allows better stabilization of the glass fibers. From these zones, each strand is then drawn by a single jet stream and thus subjected to primary stretching. However, according to a preferred embodiment of the invention and in order to obtain finer fibers, the above-mentioned main gas flow is also used in connection with the secondary jets and the associated control element. Each glass fiber that is entrained by the jet stream and partially stretched therein then enters the interaction zone formed with the main stream and becomes stretched therein in a second step, as will be explained below.

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Although the method first directs the glass strands between the jets before entering the jets, the method allows very efficient stabilization of the glass feed due to the location of the laminar flow zones on a fixed mechanical structure, namely the surface of the guide member.

The device according to the invention for producing fibers from a stretchable material by the method according to the invention comprises at least one gas jet generator device provided with outflow openings and a source of stretchable material, the device being characterized in that the gas jet outflow openings are laterally spaced from the guide member. located very close to the gas jets and having a convex surface that changes the direction of the gas jet trajectories, and that the stretchable feed source is located opposite the convex surface of the guide member to direct material strands to currents induced by possibly further comprising a generator which generates a main gas flow having a cross-section greater than that of the gas jets and directed transversely to the gas jets which have been reoriented, and interrupts their course.

The following description, given in connection with the accompanying drawing, clearly illustrates the advantages of the invention and its various objects, and in particular explains the stretching in two steps without interruption of the strands of the material to be stretched.

Figure 1 is a schematic vertical view of the main parts of a fiberizing and fiber receiving device according to the invention, with certain parts in section.

Figure 2 is a schematic perspective view, on a larger scale, of the main parts of a defibering device comprising a plurality of defibering centers, certain parts shown cut away and other parts broken away to show certain features of the system.

Fig. 3 is a vertical sectional view, on a larger scale, of 5 6281 3 in a plane passing through the outlet of the jet, and shows the various members of the defibering center.

Fig. 4 is a sectional view similar to Fig. 3, but taken in the plane of the glass feed nozzle, i. in a plane between two outlet nozzles of a neighboring jet.

Figure 5 shows in detail certain dimensions that must be taken into account in order to provide the operating conditions associated with the preferred embodiment of the invention for the defibering center.

Fig. 6 is a schematic elevational view taken along line VI-VI of Fig. 5, and

Fig. 7 is a horizontal sectional view taken along line VII-VII and also shows some dimensions to be considered.

Let us first consider Figure 1, in which reference numeral 10 denotes a generator such as a burner provided with a pipe 11 from which the main stream B exits. This main stream generator is supplied with air and fuel together via 12.

Figure 2 shows the jet outlets 22a, 22b, 22c, 22d, 22e and 22f through which the jets leave the junction box 13. · These adjacent openings are spaced apart and along a convex guide member 14. Their extent is greater in the direction of the encounter edge of the guide member than it. in a perpendicular direction. In addition, their planes of symmetry are perpendicular to the guide member and preferably parallel to each other.

According to a preferred embodiment of the invention, the outlets of the jets are practically rectangular, and the relationship between the two dimensions of the holes is shown below in connection with Figures 5 and 6.

Figures 1-4 show that the jets b, c, d and e originate near the intersecting edge of the initially curved guide member 14 and in a direction substantially tangential to the surface of the guide member, and the core of each jet follows exactly the curved surface as shown in Figure 3. for kernel bc. Due to the position and shape of the outlet openings such that a larger dimension of each jet is in contact with the curved guide surface, the jets are exposed to the Coanda effect, i. they flow while remaining in contact with the curved surface of the member 14 and thus have to change direction along a path 6281 3 6 which substantially follows the curvature of said surface. At the same time, the flow of each jet, for example the jet leaving the opening 22b, causes the surrounding gas or air to be absorbed, the combined effect of the change of direction and the absorbed air causing the two vortices schematically shown for jet b in 23b-23b in Fig. 2, where this shower is shown in an exploded view. Arrows in Figures 2, 3 and 4 represent the streams of absorbed air,

As shown in Fig. 2, the direction of rotation of the vortices 23b is downward at the side edges of the jet b in particular and at the side edges of each jet in general. Due to the fact that the outlets of the jets are laterally spaced apart, ambient gases or air are entrained between the two adjacent jets; they flow almost laminarly along the surface of the control member 1 * J, and in the same general direction as the showers. These regions of the laminar flow are shown in Fig. 2 by broken lines on the surface of the control member, and are characterized by a relatively low pressure and a certain stability, i.e. rather turbulence. The molten glass feed nozzles 16 are positioned between the jets, preferably at positions such that the glass strands are fed into the laminar flow zones between the jets. The glass is fed from a source schematically shown at 15 and includes a traction plate 17 with a series of feed nipples spaced apart. The molten glass flows into the feed nipples 16 terminating in the openings 25, which makes it possible to obtain in a preferred manner either glass droplets or thinning glass cones T which are converted into glass fibers S. Figure 2 shows a series of these cones Tb, Te, Td and Te, each located between two adjacent jets in the current plane, and as can be seen, the cone Tb generates a glass fiber which is subsequently subjected to jet b, while the cones Tb and Td generate glass fibers which subsequently penetrate the currents of jets c and d, respectively. In order to distribute the glass strands in this way in the respective jets, the glass feed nipples 16 and thus also the cones T are preferably positioned displaced towards one of the two neighboring jets, while remaining in planes located in the plane between these jets, as described above. This asymmetrical location of the feed nipples will be discussed in more detail later in connection with Figure 6. This asymmetry is highly desirable to ensure that each glass fiber is exposed to the intended shower.

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Fig. 3 is a schematic view of the plane of symmetry of the outlet opening 22b corresponding to the jet b; however, the feed nipple 16, the glass cone Tb and the thread S entering the jet b are shown in this view uncut. Instead, the sectional view of Fig. 4 is taken from the plane of symmetry of the feed nipple 16 forming the glass cone Tb, so that these are shown therein.

As for the glass fiber, its lower part S1 is shown in Fig. 4 by broken lines to show that it is then located in the plane of the jet b and that this jet thus conveys the fiber to the interaction zone formed with the main current B.

The representation of the flow of each jet in Figure 2 is to be interpreted as follows: In the region of the downstream side of the control member 14, the vortices are particularly well formed and reach their maximum power at 23b.

Their intensity then decreases as the jets advance downwards and this decrease in intensity is indicated by poorly defined lines 23c in the area where the jet c is shown in scattered view, i.e. approximately halfway between the downstream edge of the control member 14 and the area where the jet penetrates.

Despite the fact that the intensity of the vortex movements decreases in each jet and that the vortices mix with other parts of the flow and merge, each jet, as it approaches the main stream, still has enough kinetic energy to be able to penetrate the main stream and form vortex pairs 24b, 24c, 24d. In other words, the combined flow thus has an even higher kinetic energy per unit volume than the main flow. The manner in which these vortices are formed in the interaction zone has already been described in detail in the above-mentioned patent applications or publications, so it suffices to recall here that not only the relationship of kinetic energies Preferably, the perpendicular cross-section of the secondary jet is smaller than that of the main stream.

One feature of the jet delivery system described above relates to the dimensions of the jets and corresponding outlets. In fact, it is recommended to use outlets which extend in the longitudinal direction of the guide member than in the direction perpendicular to the guide member, and which are preferably rectangular.

This shape promotes the retention of the jets on the guide surface and the development of the desired pairs of vortices in each jet. It should be noted, however, that it is also possible to use square outlets, but that such an implementation differs from the optimal operating conditions.

Furthermore, it should be noted that vortices are formed according to the present invention without the need to use the collision of neighboring jets with each other rather than the mechanical structures located along the side surfaces of each jet to channel the jets. This feature makes it possible to select any distance between the jet outlets, provided that the distance is long enough to allow on the surface of the guide member 14 between adjacent jets the areas where the absorbed ambient gases form the laminar flow zones into which the glass threads are fed.

Thanks to the embodiment of the invention described above, which is characterized by the formation of laminar flow zones on the surface of a device immovable relative to the device, namely a convexly curved guide member 14, very high stability can be achieved not only for these zones but also for adjacent jets.

The kinetic energies of the jet and the main stream are affected by numerous factors, especially their velocities and their temperatures. In fact, since the density of gases varies with their temperatures, temperatures are the determining parameter. In some patents, including the aforementioned patent 2,222,318, the temperature of both the jet and the main stream is much higher than ambient temperature, e.g. on the order of 800 ° C and 1580 ° C, respectively, but in many cases a jet with a much lower temperature is preferred, e.g. temperature. It will then be possible to use any air source instead of a burner or any other heating element to supply the jet with gas. In addition, the speed of the jet can be reduced even lower than the speed of the main stream, still allowing it to retain sufficient kinetic energy to be able to penetrate the main stream and form an interaction zone comprising vortices used to stretch the glass fiber in the main stream.

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It is also recalled that the jets associated with the curved control member and the special placement of the glass feed described above can be used alone to perform stretching, but are preferably supplemented and combined with the jets to expose the glass filament in this case to two stretching stages. in the jet-mainstream interaction zone.

Reference should now be made to Figures 5 »6 and 7 to specify some parameters. Figure 5 schematically shows the main components of a defibering system according to the invention, namely a main current generator, a jet transmitter, a convex control member which changes the direction of flow and forms vortices in the jet, and a source of stretch material supply. It is marked, as well as in Figures 6 and 7, by symbols representing certain parameters, such as longitudinal and angular dimensions, for which the following tables show the appropriate ranges of both longitudinal dimensions and angles and their preferred values.

Table I

Stretch material pull plate and feed nipples.

Symbol Default value (mm) Range dT 2 1-5 1T 1 1-5 1R 5 0-10 dR 2 1-5

Dr 5 1-10

Table II

Shower transmitter and convexly curved control element.

Symbol Primary value (mm, degrees) Range dJ 2 0.5 ~; 4

Dj 5 1 - '4 YJJ 2 1 - 10 6281 3 10

Table II (continued) YJF 2 v 1 «.

rd 2 2 2 2> 5 oD 45 30 - 90 otJB 45 20 - 90

As shown in Figure 6, the distance between the glass feed holes is substantially equal to the distance between the planes of symmetry adjacent to the jet transmission apertures. In addition, each glass feed nipple is located so as to feed a glass filament S between two adjacent jets into a zone of laminar flow covering the curved guide member 14, but preferably at a position slightly offset to the center. as a result, it is always exposed to the flow of the nearest jet in a very stable manner.

Table III Main current

Symbol Primary value (mm) Range lg 10 5 - 20

Table IV

Mutual positions of different bodies

Symbol Primary value (mm) Range ZJF 5 1 - 15 ZT_ 20 12 - 30 XBp

Xjp 5 o - 10

The number of defibering centers can be as high as 150, but in a normal defibering plant for glass or some similar thermoplastic material, a valid draw plate comprises about 70 feed nipples.

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The term "feed opening" for the stretchable material used in the specification must be interpreted in a very general sense; it may in fact mean a separate opening or series of openings, or a feed gap associated with a series of jets flowing along the curved guide member. In the case where the feed openings are replaced by a slot, this is located transversely to the main stream and preferably downstream of the jet series associated with the control member, the stretchable material coming from the slot splitting into a series of cones and strands under jets and associated currents.

It should also be noted that the operating conditions of the system of the present invention vary depending on many factors, for example, the properties of the material to be fiberized.

As mentioned above, the invention can be applied to the stretching of widely varying stretchable materials. The temperature of the drawing plate, i.e. the feed source, will of course vary according to the material to be defibered in each case, and when stretching glass or other inorganic thermoplastics, it will vary in a temperature range of about 1 * 100 ° C to about 1800 ° C. With a glass type of the usual type, the temperature of the drawing plate is about 1480 ° C.

The unit flow rate can vary between 20 and 150 kg per hole in 2 * 1 hour. 50 - 80 kg per hole in 2 * 1 hour represents typical values.

Some values for jet and main flow are also important, as shown in the following tables, which use the following symbols: P = pressure T = temperature V = velocity p = volumetric mass

· », I

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Table V Shower transmission

Symbol Primary value Range

Pj (baria) 2.5 1-50

Tj (° C) 20 - i860 VJ (m / sec) 300 200 - 900

PjVj2 (baria) 2.1 0.8 - Ho

Table VI Main current

Symbol Primary value Range ρβ (mbar) 95 30 - 250 TB (° C) IH50 1300 - 1800

Vg (m / s) 320 200 - 550 pgVg2 (bar) 0.2 0.06 - 0.5

When both gas jets and the main stream are used at the same time, each jet has, as mentioned above, a higher kinetic energy per unit volume than the main stream; for example, a jet is used whose kinetic energy per unit volume is about 10 times that of the main stream.

Claims (12)

13 6281 3 A method for producing fibers from a stretchable material by means of gas streams, characterized in that a plurality of adjacent gas jets are developed at a distance from each other and against a convex guide surface, the direction of the gas jets and their induced currents the currents form laminar flow zones on said guide surface between adjacent jets, and that the strands of stretchable material are fed between the gas jets, into the laminar flow zones, said strands being larger than the gas jets and possibly stretched therein, and that directed transversely to the jets of gas which have been reoriented so that the kinetic energy per unit volume of each jet of gas is greater than that of the main flow, so that gas jets can penetrate it and form interaction zones into which the partially stretched strands of material are fed for additional stretching. Method according to Claim 1, characterized in that the dimension of the cross-section of each gas jet in the longitudinal direction of the guide surface is greater than in the direction perpendicular thereto. Method according to Claim 1 or 2, characterized in that the syrammetry planes of the gas jets are perpendicular to the convex guide surface. *}. Method according to one of the preceding claims, characterized in that the strands of stretchable material are fed to the zones of laminar flow at points offset from planes equidistant from two adjacent gas jets. Method according to one of the preceding claims, characterized in that the path of the gas jets which have changed direction is directed downwards, towards the main stream. 6281 3 14 Method according to one of the preceding claims, characterized in that the temperature of the gas jets is close to ambient temperature. Apparatus for producing fibers from a stretchable material by a method according to any one of claims 1 to 6, comprising at least one gas jet generator device provided with outflow openings and a source of stretchable material supply, characterized in that the gas jet outflow openings (22) are laterally spaced apart and located along a guide member (14) located very close to the gas jets and having a convex surface that changes the direction of the gas jet paths, and that the stretchable material supply source (16, 17) is located opposite the convex surface of the guide member to direct material strands the gas jets are induced in zones located between the gas jets on the convex surface of the control member, and that the device optionally further comprises a generator (10, 11) which generates a main gas flow (B) having a larger cross-section than the gas jets and directed transversely to the gas jets of whose direction has been changed and interrupts their course. Device according to Claim 7, characterized in that the extent of the outlet of each gas jet in the direction of the control element (14) is greater than in the direction perpendicular thereto. Device according to Claim 7 or 8, characterized in that the abutment edge of the guide element (14) is adjacent to the gas jets flowing on its convex surface, and in that the stretchable substance supply openings (25) located between the gas jets are offset from the center. Device according to one of Claims 7 to 9, characterized in that the planes of symmetry of the outflow openings of the gas jets are perpendicular to the convex guide element (14). Device according to one of Claims 7 to 10, characterized in that each gas jet outlet (22) is substantially rectangular. 15 6281 3 Device according to one of Claims 7 to 11, characterized in that the outflow openings (22) of the gas jets are located such that one of the interfaces of the gas jets is substantially tangential to the part at the meeting edge of the convex guide surface (14). Fatentkrav