GB2025391A - Method and Apparatus for Producing Glass Filaments - Google Patents

Abstract

A method and apparatus for producing glass filaments in which glass filaments in a spinning chamber are contacted by a mist comprising a mixture of compressed air and a treatment liquid, the constituents of the mist being mixed in a first part of a heat exchanger adjacent the spinning chamber and passing to a second part of the heat exchanger more remote from the spinning chamber before being delivered from that second part into the spinning chamber. <IMAGE>

Description

SPECIFICATION Method and Apparatus for Producing Glass Filaments Technical Field of the Invention The invention relates to a method and apparatus for producing filaments from streams of liquid glass which solidify in air, are drawn out and are drawn off as filaments, and a gas or gas mixture, which assists in drawing off and/or treats the produced filaments, is introduced through a pipe system to a spinning chamber which is exposed to heat radiated by a device for liquifying the glass, is heated by the radiated heat and is discharged after heating.

Background Art A method of the above-described kind is generally used to a large extent for production of fine-gauge glass filaments and at present a vessel of heat resistant material, fed intermittently or continuously with raw glass material at the rate of consumption, is often used. Glass rods, which are arranged adjacently in several rows in a battery and whose ends, advanced continuously to match the consumption, are melted off by a heating device, are only rarely used to this end.

It is also known for a gas or gas mixture which assists in the drawing off of the filaments and/or in the treatment of the filaments to be supplied to the chamber, the so-called "spinning chamber" which adjoins the outflow ports in the drawing direction and is exposed to the heat radiated by the vessel containing the apertures (for example German Offenlegungsschrift 24 60 270 and US Patent specification No. 3 248 192).

German Offenlegungsschrift 22 11 150 also discloses a method and apparatus adapted to supply to the spinning chamber a carbonaceous or carbon-like material for depositing on surface that are not to be wetted by means of a gas or gas mixture. The non-wetting material is supplied as far as possible directly to the discharge port for preventing the external surface of spinning nozzles or flow apertures being wetted by the glass. To this end an inert gas with a comparatively small quantity of an organic gas, for example hydrocarbon gas, containing a hydrogen component in the region of the glass streams, is supplied thereto. Both gases are dissociated by heat.The gas or gas mixture is supplied by means of tubes which extend along the length of the glass vessel and are possibly situated at an angle to the filament planes and in which the top curvatures disposed nearest to the spinning ports and therefore also nearest to the hottest region of the spinning chamber, have a plurality of discharge slits.

Since only a single flattened, radiator like distribution pipe is provided for producing each gas stream, which is divided into slits and the hottest components of the gas tend to rise upwardly and the colder components tend to descend, the distribution within the pipes will be such that the coldest parts of the gas will be disposed at the bottom and the constituents already practically dissociated will be disposed at the distributor slits. This is detrimental because it does not preclude nonevaporated gas accumulating in the bottom part of the pipes, in other words it is not constantly consumed and since the regions of the pipes which are in any case situated closest to the hottest region of the spinning zone and also carry the hottest part of the gases, will be exposed to premature destruction due to the effects of heat. Demixing is also encouraged thereby.

Furthermore, the previous process is subject to distribution problems. The closer the distance between the gas mist, which flows upwardly into the slits, and the discharge ports for the glass and therefore the filaments which are possibly not completely solidified at this place, the less time and space will there be available for the gas mist to spread laterally in a distributing manner. It should also be taken into account that the glass filaments which are continuously drawn off at a high speed produce a constant air stream oriented in the delivery direction, which air stream takes up and entrains the mist as soon as it reaches it.

Disclosure of the Invention It is therefore an object of the invention to provide a method and apparatus in which the use of existing heat is optimised while the device intended for performing th'e method and expnsed to the heat radiated by the spinning chamber is largely protected and which ensures that the generated gas mist is distributed so as to cover the entire spinning chamber.

According to one aspect of the invention there is provided a method of producing glass fibre filaments comprising the steps of drawing molten glass through a nozzle or nozzles into a spinning chamber and contacting the filament(s) in the spinning chamber with a mist (as herein defined) the mist consisting of a gas under pressure and a liquid which are mixed in a heat chamber prior to contacting the filament(s) the gas and liquid entering a first part of the heat chamber adjacent the spinning chamber and passing to a second part of the heat chambers remote from that chamber before entering the spinning chamber as the mist.

According to a second aspect of the invention there is provided apparatus for producing glass fibre filaments, comprising a vessel which is surrounded by a heat resistant covering receives liquid glass and has an opening in its base through which a glass filament or glass filaments is or are drawn off from the vessel and a heat exchanger comprising at least two parts one of which is connectable with a source of compressed gas and a supply duct for a liquid and is disposed closer to the spinning chamber than the second part which is provided with apertures through which a mist of mixed compressed gas and liquid can pass to the spinning chamber.

The generated mist mixture may be blown against a distributor surface.

The description of the invention is directed to a vessel which is continuously supplied with raw glass material. The molten glass, divided into individual streams, flows from apertures in the bottom of the vessel and forms a so-called spinning cone on the outside of the aperture. The individual streams solidify in air and thus form the glass filaments which are drawn off and are further processed continuously, for example by a drawing capstan, reel or the like. Two embodiments of apparatus for performing a method according to the invention are hereinafter described, by way of example with reference to the accompanying drawings.

Brief Description of the Drawings Figure 1 is an embodiment of apparatus according to the invention shown highly schematically in partial vertical section; Figure 2 is another embodiment of apparatus according to the invention shown in schematic form corresponding to Fig. 1 but to a smaller scale; and Figure 3 shows a substantial component part of apparatus according to Fig. 2 as seen in the direction of the arrow III of Figure 2.

Best Modes for Carrying out the Invention Referring to the drawings, the apparatus shown in Figure 1 comprises a jacket 1 of refractory material, retained together by a sectional frame and incorporating a so-called nozzle strip 2 of platinum or a platinum alloy, which is open at the top so that it can be intermittently or continuously supplied with raw glass at the rate of consumption defined by the filament draw off, for example in accordance with the German Offenlegungsschrift 2 326 975. The bottom of the nozzle strip 2 is provided with flow apertures, in this case in the form of so-called spinning nozzles 3 on each of which there is formed a spinning cone 4 from which a filament 5 is continuously drawn off.Since the temperature in the nozzle strip 2 varies between 1 0000C and 12500C and the bottom 6 of the nozzle strip 2 cannot be covered by the jacket 1 of refractory brick, it follows that a relatively high temperature, resulting from radiated heat, will prevail in the space beneath the apertures or spinning nozzles 3, the so-called spinning chamber 7.

A heat exchanger, referenced generally with the numeral 8, which is supplied with compressed air from a source (not shown) is provided for filling the spinning chamber 7 with a mist which surrounds the individual filaments including the filaments which are paid off within the filament column. The term "mist" in this specification generally refers to a gas or a gas mixture or an evaporated liquid, which can be a lubricating oil, an antistatic, but also simply water or a mixture, which is brought to discharge. With the mist deposited on the paid off filaments the latter can be lubricated and/or prevented from acquiring an electrostatic charge.

In the exemplified embodiment illustrated in Figure 1 the heat exchanger 8 is partially recessed into the underside of the jacket 1 adjacent to the nozzle strip 2 and comprises a first part in the form of at least one mixing tube 9 and a second part in the form of a delivery tube 10 both of which are interconnected by a bend 11.

Compressed air at a pressure of approximately 0.5 bar and then the treatment fluid, for example, a lubricating oil, is introduced into the mixing tube 9. These two components enter as a relatively cool media into the mixing tube 9 which is disposed closest to the hotter part of the spinning chamber 7, are heated in the tube 9 and are evaporated as an air-liquid mixture, then pass into the colder region 10 of the heat exchanger 8 which is remote from the spinning chamber and emerge through nozzle apertures or the like 1 2. In this way the temperature difference between the media intended to produce a gas mixture adapted to assist in the drawing off of the filaments and/or for treating the produced filaments is used for cooling the parts of the heat exchanger disposed closer to the hotter part of the spinning chamber.

The mist existing the nozzles 12 strikes a distributor surface, in this case in the form of a screen wall 13, and distributes itself on the surface over the length of the tube and over the width of the nozzle strip 2 and passes through the screen mesh and is entrained on the rear (to the left as viewed in Figure 1) of the distributor surface by an airstream 14 generated by the filament drawn off, thus enveloping the individual filament 5.

Compressed air and liquid can also be mixed prior to entering the tube 9. Referring now to Figures 2 and 3 there is provided a heat exchanger 15, into which compressed air is initially introduced at 1 6 from a source (not shown). Cold air flows through an iniet tube 1 7 and then passes into a first part or mixing tube 1 8 to which the treatment liquid is supplied through a supply tube 19. From the mixing tube 18 8 the heated mixture which is to be evaporated passes via an intermediate tube 20 into a second part or delivery tube 21 from ports 21' of which the mist emerges.

The tube arrangement in this embodiment is also such that the hottest part, adjacent the spinning chamber is cooled by the (cool) constituents of the mist to be formed. To this end the tubes 17, 18 and 20 are mounted on the outside of a member 22 which is associated with a sheet metal bracket 23 and extends at an angle therefrom.

Furthermore the heat exchanger 1 5 in this embodiment is constructed as an interchangeable unit namely in that the sheet metal bracket 23 can be inserted by means of a horizontal member 24 thereof on rails 26 formed by brackets 25, mounted on the machine frame until it reaches a stop abutment, for example when it bears with its side wall end face 27 against the external wall of the refractory cladding 28 of the nozzle strip 29.

To accommodate this, the delivery pipe 21 disposed at the greatest vertical and horizontal distance from the hottest region of the spinning chamber is suspended in lugs 30 attached to the underside of the horizontal member 24.

Owing to being heated on its path from its entry through the tube 1 6 to the delivery tube 21, the compressed air loses part of its pressure but this pressure is sufficent to thrust the mixture through the tubes of the heat exchanger and to discharge it as a mist from the ports 21'.

The emerging mist is blown on to a distributor device 31. The device 31 comprises a sheet metal plate 32 which rises to the right (as viewed in Figure 3) at an angle in the direction towards the nozzle strip 29.

Since the mist is blown against a wall formed by the sheet metal plate 32 the mist is distributed over the width of the plate. If the ports or spinning nozzles 33 are arranged in groups, so that a distance equal to the width of one nozzle or more is always provided after every five, six or more spinning nozzle of a row of a total of, for example.

12 rows, it is possible for ribs 32 to be placed upon the plate 32 to guide the mist towards the groups.

As is the case with the embodiment of Figure 1 the mist which rises upwardly is entrained by the air stream generated by the drawn off filaments.

The distributing device 31 can also be constructed as an interchangeable unit and to this end can be adapted to slide on supporting brackets 35 which are mounted on the machine frame.

Although it is usually sufficient if the mist is supplied from one or both sides of the spinning chamber it is also possible for additionai delivery tubes to be disposed in intermediate zones beneath the nozzle strip if the width thereof, resulting from the large number of rows of spinning nozzles, would no longer ensure distribution of the mist from the outside into the middle rows of filaments. The discharge apertures can then be arranged to be offset relative to both sides and the guiding device, for example corresponding to the sheet metal plate 32 according to Figure 2, taking the form of a Vshaped plate, can then distribute the generated mist to both sides.

The invention may be summarised in the following summaries:- 1. A method for producing filaments in a spinning chamber from streams of liquid glass which solidify in air, are drawn out and are drawn off as filaments, comprising distributing a gas or gas mixture, which assists in drawing off and/or treats the produced filaments, through the spinning chamber, the mixture being exposed to heat radiated by a device adapted for liquifying the glass, is heated by the radiated heat and is discharged into the spinning chamber after heating, the mixture consisting of air or a conveying gas under pressure and a liquid which are introduced to a member adjacent the hottest part of the spinning chamber discharged from the mixer as a mixture remote from the hottest part of the spinning chamber.

2. Method according to Summary 1, characterised in that the generated mixture mist is blown against a distributor surface.

Claims (13)

Claims

1. A method of producing glass fibre filaments, comprising the steps of drawing molten glass through a nozzle or nozzles into a spinning chamber and contacting the filament(s) in the spinning chamber with a mist (as herein defined), the mist consisting of a gas under pressure and a liquid which are mixed in a heat exchanger prior to contacting the filament(s), the gas and liquid entering a first part of the heat exchanger adjacent the spinning chamber and passing to a second part of the heat exchanger remote from that chamber before entering the spinning chamber as the mist.

2. A method according to Claim 1, in which the mist is distributed in the spinning chamber by a distributor surface.

3. Apparatus for producing glass fibre filaments, comprising a vessel which is surrounded by a heat resistant covering receives liquid glass and has an opening or openings in its base through which a glass filament or glass filaments is or are drawn off from the vessel, and a heat exchanger comprising at least two parts one of which is connectible with a source of compressed gas and a supply duct for liquid and is disposed closer to the spinning chamber than the second part which is provided with apertures through which a mist of mixed compressed gas and liquid can pass to the spinning chamber.

4. Apparatus according to Claim 3, in which the first and second parts each comprises a tube.

5. Apparatus according to Claim 3 or Claim 4, including a distributor surface between the second part and the spinning chamber for distributing the mist over the spinning chamber.

6. Apparatus according to Claim 4 and Claim 5 in which the first part comprising a mixing tube, with the supply means for the liquid medium, is disposed between a supply pipe for compressed air and an intermediate pipe.

7. Apparatus according to any of Claims 4 to 6, in which the tubes are mounted on a substantially vertical member which is oriented at an upward angle towards the base of the glass-holding vessel and is associated with a bracket forming an interchangeable unit, whose horizontal member bears slidably on support brackets.

8. Apparatus according to Claim 7, the bracket being a sheet metal bracket.

9. Apparatus according to any of Claims 5 to 8, in which the distribution surface comprises a screen wall.

10. Apparatus according to any of Claims 5 to 8, in which the distribution surface comprises a sheet metal plate which rises at an angle towards the base of the glass-holding vessel.

11. A method of producing glass-fibre filaments, substantially as hereinbefore discribed with reference to and as shown in Figure 1 or Figures 2 and 3 of the accompanying drawings.

12. Apparatus for producing glass fibre filaments, substantially as hereinbefore described with reference to and as shown in Figure 1 or Figures 2 and 3 of the accompanying drawings.

13. Glass fibre filaments whenever produced by a method according to any of Claims 1,2 or 11 or using apparatus according to any of Claims 3 to 10or12.