FI57396C - FRAMEWORK FOR THE PRODUCTION OF FIBERS WITH REGARD TO BEGRAENSAD LAENGD - Google Patents

Description

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National Board of Patents and Registration (44)]. monthMost ^ m date—

Patent · och registerstyreisen AmMom uttagd och utUkmtM pubikund 30. oU. 80 (32) (33) (31) Privilege claimed — Bugird prlorltet (71) Johns-Manville Corporation, Greenwood Plaza, Denver, Colorado 80217, USA (72) Duane Harold Faulkner, Larry Edward Howard, USA (7U) Forssen & Salomaa Oy (5U) The present invention relates to a method and a rotary fiber production apparatus for without the use of conventional external fiber thinning methods.

The disintegration of glass into fibers can be performed by a number of different methods. One method is rotary fiber disintegration. Although conventional rotary fiber splitters, e.g., rotors with 7,000 to 10,000 orifices with orifice diameters in the range of 635 to 762 microns, can produce fibers having an average diameter of about 14 microns, these conventional units cannot produce fibers with an average diameter of 7 microns. or less than the diameter size required for many commercially acceptable insulating felts. Thus, the fibers emerging from the openings in these units must be thinned to achieve the desired fiber diameter. This is usually done by hot gas blowing from a ring nozzle above and radially outwards from the circumference of the rotor. The heat from the gas prevents the fibers from solidifying while the pressure of the gas stretches or thins the fibers.

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Although the latter method produces fibers with an average diameter of 7 microns or less, it presents a variety of problems. First, the large amount of natural gas used by such a method is not always readily available and sudden interventions must be assessed in advance. As a result, production must be suspended or slowed down if a sufficient amount of natural gas or other fuel required for the process is not available.

Secondly, it is apparently desirable to eliminate the additional costs of hot gas blowing used for thinning plus maintenance and problems with the burners required in the thinner.

Third, the additional heat generated by the thinning burners must be absorbed in the assembly chamber before the fibers are padded into a mat.

U.S. Patent 3,503,726, issued March 31, 1970, is an example of the structure of a previously known spinner or rotor. The spinner disclosed in this patent has 10,000 orifices, each of which is about 635 to 762 microns in diameter. The patent says nothing about the diameter of the fibers produced. U.S. Patent 3,644,108, issued February 22, 1972, discloses an apparatus for producing fibers by centrifugal force, but does not provide any indication of the number of openings in the spinner, their diameter, or the diameter of the fibers produced.

It is an object of the invention to produce continuous or limited length fibers with an average diameter of 7 microns or less by conveying the molten material only through very small openings in the rotor to the surrounding atmosphere.

The present invention provides a method of making staple fibers of limited length and having an average diameter of less than about 7 microns from molten mineral material by continuously feeding hundreds of kilos per hour of said molten material into a rotating rotor within its circumferential wall. The circumferential wall has openings up to 450 microns (0.018 inches) in diameter. Said molten material is passed through said openings to form primary fibers of an average diameter of less than about 7 microns without the use of hot gas blowing thinning. The method according to the invention is characterized in that in the method a series of moving gas flows are formed around said circumferential wall at a distance therefrom, separated by a number of relatively stationary zones, the gas of said flows moving in a direction perpendicular to the direction of in contact with said moving gas streams 3 57396, the temperature and velocity of the gas flow being sufficient to break the primary fibers into staple fibers but insufficient to cause significant thinning of the fibers.

The invention also provides an apparatus for forming staple fibers of an average diameter of less than about 7 microns from molten mineral material hundreds of kilograms per hour, in which molten mineral material is fed to a rotating rotor inside its circumferential wall and the circumferential wall has openings of up to 450 passing through openings to form primary fibers without the use of hot gas blowing thinning. The device according to the invention is characterized by a gas flow distributor for cutting primary fibers into staple fibers spaced around a circumferential wall and comprising an annular distribution tube and nozzles hanging from the lower surface of the distribution tube, their blowing ends being in a plane substantially parallel to the circumferential rotor with.

By directing numerous air currents with a relatively low temperature, e.g. 65.6 ° C or less, around the circumference of the rotor at circumferentially spaced fibers in a direction perpendicular to the direction of travel of the fibers as the fibers emerge from the openings, the fibers can be cut to suitable lengths. to form a uniform felt, which felt has the desired properties of conventional insulation.

In this system, the fibers continuously emerge from the openings and as the fibers pass through the air flow, they break and travel down to the assembly chamber where the fibers are formed into a felt. Due to the low temperature of the airflows and the ambient air around the rotor, the glass fibers are not soft enough for a long time to thin when the air charges hit them, but instead these forces break the fibers.

The diameter distribution of the finite length fibers produced by the method and apparatus of the present invention is narrower and the fibers are longer in length than the finite length fibers produced by the prior art methods in which external torch thinning has been used in the prior art methods. The method and apparatus of the present invention have achieved a commercially viable production volume. The fibers produced have an average diameter of 7 microns or less and no secondary thinners are required.

In this application, when referring to fiber diameter, the term "average diameter" is used in the sense of conventional arithmetic or mean diameter, which is obtained by averaging the results of a microscopic assay.

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Figure 1 shows a side view of a device according to the present invention located above a collection chamber, which is shown in cross-section.

Figure 2 shows a sectional view of a device according to the present invention.

Figure 3 is a bottom view of the device of the present invention taken substantially along line 3-3 of Figure 2.

Figure 4 shows a partial view of a rotor edge portion used in the apparatus of the present invention.

Figure 5 shows a partial cross-sectional view of the rotor rim and illustrates the accumulation of glass on the inner surface of the rim and the openings in the rim.

Figure 1 shows an apparatus 20 according to the present invention above the assembly chamber 22. The apparatus 20 comprises a fiber disintegration unit 24, a supply pipe 26, a heater structure 28 and a compressed air device 30. The apparatus 20 is supported on a conventional lattice frame. However, in order to better represent the device according to the present invention, the lattice frame is omitted from the drawing.

As a fiber, the spreader 24 includes a drive shaft 32 supporting a spinner or rotor 34. The drive shaft is supported and pivotally mounted inside the tubular sheath 36 by two bearing devices 38 (only one of which is visible) which bearings are attached to the tubular sheath 36. The upper portion of the drive shaft 32 is pulleyed 40. The pulley is connected to a variable speed motor 42 or other conventional drive by means of a drive belt 44, and thus the motor 42, which drives the drive shaft 32, causes the spinner 34 to rotate.

The rotor 34 comprises a plate 46, a circumferential wall of the rim 48 extending upward from the circumference of the plate 46, and a reinforcement 50 extending inwardly from the upper edge of the circumferential wall 48. The rotor has a centrally located hole through which the threaded portion of the drive shaft 32 passes. A nut 52 in the threaded portion of the drive shaft secures the rotor plate between itself and the pension 54 on the drive shaft. The plate 46 forms the base of the rotor. The lower edge portion of the circumferential wall 48 is welded or otherwise attached to the circumference of the plate 46. The upper edge portion of the circumferential wall 48 is welded or otherwise attached to an annular reinforcing ring 50 which provides the rotor with the necessary strength as it rotates at high speeds at temperatures that tend to weaken the metal of the circumferential wall.

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The circumferential wall 48 of the rotor is provided with a plurality of openings 60 having a longitudinal axial direction extending radially through the circumferential wall 48.

In order to form fibers having an average diameter of 3 to 5 microns by passing glass through the openings at a rate of 272.2 to 544.3 kg per hour and outside the circumferential wall into the ambient air, it is preferred that the circumferential wall have at least 40,000 to 70,000 openings. the diameter of the orifice is on the order of 254 to 356 microns. The distance between the diameters of the openings is typically 0.091 1 0.025 cm. The applicant has also been able to produce fibers with an average diameter of about 3.5 to 7 microns at a rate of 136.1 to 362.9 kg per hour, with as few as 12,000 orifices each having a diameter of 508 microns in the rotor. At the lowest flow rates, fibers with a diameter of one micron or less can be produced by a rotor with apertures of 51 microns or less in diameter. Such a rotor requires a large number of orifices (e.g., producing fibers with a diameter of 0.5 microns at a flow rate of 18.1 kg per hour requires a rotor with 200,000 to 250,000 orifices).

The heater device 28 comprises a distribution tube 62 provided with a plurality of commercially available radiant burners 64 positioned to direct their heat outwardly from the distribution tube at an angle of about 45 degrees to the vertical. In this orientation, the burners are directed to the rotor circumferential wall 48 to maintain the rotor circumferential wall at sufficiently high temperatures to maintain the glass inside the rotor and the inner surface of the wall at temperatures sufficient to maintain the glass viscosity within the fiber forming range. For typical glass compounds used, the temperature of the rim or circumferential wall is usually maintained at about 927 to 1149 ° C. The fuel gas mixture is fed to the distribution pipe 62 via a supply line 66. The distribution tube is usually ring-shaped, but is cut at a point that allows the feed tube 26 to be mounted to feed glass to the rotor.

The feed tube 26 receives molten glass from a suitable invisible feeder such as a preheating furnace, other equipment that can feed purified glass from a conventional melting furnace, or an electric furnace. The feed tube 26 feeds molten glass to the rotor plate 46 at a location away from the center of the rotor. Due to the centrifugal force caused by the rotation of the rotor, the glass flows towards the circumferential wall of the rotor and upwards from the inner surface of the circumferential wall. Once a sufficient amount of "h" has accumulated on the inner wall of the rotor, the glass is forced to pass through the openings to form continuous fibers with an average diameter of 7 microns or less.

The compressed air device 30 comprises an annular distribution pipe 68, the supply line 70 of which connects to a conventional invisible source of compressed air. A plurality of tubes or nozzles 72 depend on the lower surface of the distribution tube 68. The discharge ends of the nozzles are located in a plane substantially parallel to the plane formed by the upper edge of the circumferential wall 48 of the rotor, i.e. in a horizontal plane located only a few inches above the plane formed by the upper edge of the rotor wall. The nozzles 72 are circumferentially spaced around the circumference of the spinner so that the nozzles are located approximately 2.5-3.75 cm radially outward from the rotor.

The nozzles 72 are located relative to each other so that there are zones of relatively static air between adjacent airflows, which airflows flow downward from the nozzles 72 past the rotor 34. For example, in a 30.5 cm diameter spinner, the dispensing tube 68 is typically 38.1 cm in diameter and is provided with 20-24 nozzles. The air coming from the nozzles is also typically at a pressure of about 3515.5 kg / m.

From the rotor, the circumference of which is surrounded by circumferentially spaced nozzles 72, a series of impulse-like forces are applied to the fibers emerging, separated by areas of relatively static air. In this way, impulsive forces impinge on the fibers and break the fibers to form fibers of limited length. By placing the nozzles farther apart around the circumference of the rotor, longer fibers of limited length can be obtained. Up to a certain amount, the closer the nozzles are placed to each other, the shorter the limited length of fibers formed. However, if the nozzles are placed too close to each other, a substantially continuous air curtain is formed around the circumference of the rotor and the fibers are not broken. Instead, the fibers remain continuous and tend to entangle into a rope below the rotor and form a product that is unsuitable for a conventional felt.

Although air is preferred for fluid flows that break continuous fibers, fluid flows may be other gases or liquids. In the manufacture of fibers of limited length by this method, air currents are generally directed at the fibers at substantially right angles to the direction of travel of the fibers, and the air flows are spaced such that impulsive forces are applied to the fibers. As mentioned above, if the adjacent nozzles are not sufficiently spaced apart, there is no zone of relatively static air through which the fibers pass and whereby the fibers are subjected to a constant force which merely directs them downward and allows them to entangle into a rope. Impulsive force, on the other hand, tends to break continuous fibers into fibers of limited length.

In operation, the heater device 28 heats both the plate 46 and the circumferential wall 48 of the rotor to a temperature sufficient to keep the molten glass inside the rotor 34 of suitable viscosity to form the fiber. The molten glass is then introduced into the rotor through the feed tube 26 at a sufficient rate to ensure that the circumferential wall of the rotor is completely covered with glass to a depth or amount "h" sufficient to force glass flow through the openings to form continuous fibers of average diameter 7 microns or less. As the fibers pass outward from the spinner, they pass alternately through the airflows from the nozzles and the relatively static air between the nozzles, causing them to be subjected to impulsive forces that cut the fibers to a limited length. The air currents from the nozzles also direct the fibers down into the collection chamber 22. As soon as the fibers enter the collection chamber, they can be coated with a suitable adhesive by nozzles 74 or other conventional equipment and then collected on a conveyor belt 76 at the lower end of the collection chamber. each assembly chamber has only one fiber splitting unit, and the felt in the chamber is deposited on top of the felts of the other chambers at a location outside the assembly chamber of the single unit. In addition, a plurality of devices according to the present invention can be used in a line above one large assembly chamber, where an unlayered felt coming from the outlet of the device row is formed inside the assembly chamber.

Claims (2)

8 57396 A method of making staple fibers of limited length and having an average diameter of less than about 7 microns from molten mineral material by continuously feeding hundreds of kilos per hour of said molten material into a rotating rotor (34) within a circumferential wall (48) having apertures in the circumferential wall (48) , having a diameter of up to 450 microns (0.018 inches) by passing said molten material through said openings (60) to form primary fibers having an average diameter of less than about 7 microns without the use of hot gas blast thinning, characterized in that said circumferential wall (48) is formed. around it at a distance from it a series of moving gas flows separated by a number of relatively stationary zones, causing the gas of said flows to move in a direction perpendicular to the direction of movement of the primary fibers and subjecting the primary the fibers to pass into said stationary zones and into contact with said moving gas flows, wherein the temperature and velocity of the gas flow are sufficient to break the primary fibers into staple fibers but insufficient to cause significant thinning of the fibers. Apparatus for carrying out the method of claim 1, wherein the method produces staple fibers less than about 7 microns in diameter from the molten mineral material hundreds of kilograms per hour, wherein the molten mineral material is fed to a rotating rotor (34) within its circumferential wall (48) and the circumferential wall (48) has orifices (60) having a diameter of up to 450 microns (0.018 inches) in which molten material is passed through the orifices (60) to form primary fibers without the use of hot gas blast thinning, characterized by a gas flow distributor (30) to cut the primary fibers into staple fibers. located around the circumferential wall at a distance therefrom and comprising an annular distribution tube (68) and nozzles (72) suspended from the lower surface of the distribution tube, their discharge ends being located in a plane substantially parallel to the upper edge of the circumferential wall (48) of the rotor (34) with the aman level.