US 3114618 A
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1953 M. LEVECQUE ETAL 3,114,618
APPARATUS FOR PRODUCING FIBERS FROM THERMOPLASTIC MATERIAL Filed Feb. 21. 1956 INVENTORS. MARCEL Lsvacoua MARCEL MABRU 8 MAURICE CHARPEmmn m; w ATTORNEY United States Patent The present invention relates to the manufacture of fibers of mineral materials in the viscous state and particularly glass fibers.
It is already known, in order to produce fibers of great fineness, to subject the material projected under the action of centrifugal force to the action of gas currents discharging from a chamber fed by combustible and comburent and in which the combustion of these two elements is obtained. To accomplish this purpose a hollow body,
whose surfaces are joined along a more or less sharp edge in which are located a single row of orifices, is utilized, the hollow body being surrounded by a combustion chamber taking the shape of an annular crown whose expansion orifice in the form of a continuous slot or a series of holes projects a ring-like blast of hot gases perpendicular to the plane of projection of the filaments from the orifices. A structure of this general type is shown in United States patent to Pierre Rene Heymes and Ivan Peyches, No. 2,624,912, issued January 13, 1953. The described procedure and arrangement allows for an efiicacious drawing out of the filaments as soon as they leave the orifices, these filaments being drawn out and carried along with great force by the combustion gas escaping from the expansion orifice to form the fine fibers. However, because of the limited number of orifices provided on the peripheral edge of the rotating body, the fiber production of these arrangements is relatively low.
The present invention has for an object an improvement to the process and the arrangements noted above and permits a large and substantially uniform production of very fine fibers.
Conforming to the invention, the plastic material is projected at high temperature from a centrifugal body or element Whose peripheral or filament delivery part, which can be notably of a cylindrical shape, bears a certain number of rows of projection orifices, one above the other, for example 2 to rows. The filaments projected from the centrifugal body are subjected to the action of gases moving at high speed and high temperature escaping from the expansion orifices of an annular combustion chamber in such a manner as to effect, without the formation of either rigid or very viscous intermediary filaments, an entrainment of the filaments with an abrupt change in direction and an energetic attenuation and drawing out of the filaments so entrained, transforming them into very fine fibers. One might fear that the fact of providing two or more rows of projection orifices on the periphery of the centrifugal body might lead the fibers issuing from these orifices to stick and hinder the drawing out. Applicants have found that by distributing the projection orifices into several rows on the peripheral wall of the centrifugal body there is obtained a simultaneous drawing of the glass projected from these orifices, even if the orifices are lined up in the direction of the gas current. It has been possible, in fact, to observe exactly the different individual paths formed by the melted material projected from each orifice of the several rows of orifices.
Applicants have also found that the fibers thus formed can be drawn below the centrifugal body but may have a tendency to regroup in the still plastic or hot state. This can result notably when the centrifugal body is surrounded by a combustion chamber having as expansion orifices, a
continuous slot, or holes or slots very' close together. In these circumstances there is formed below the centrifugal body a turbulent motion of air or gases which create a low pressure zone below the centrifugal body with a tendency to carry into that zone the hot gases from the combustion chamber and hence the fibers entrained there in. This phenomenon can cause several serious drawbacks, especialy the sticking of fibers under the centrifugal body and a sticking together of the regrouped fibers and possibly collecting deformed filaments appearing as rigid and breaking small rods. These deficiencies are more noticeable as the number of orifices in the centrifugal body are increased and production of fibers enlarged.
One of the objects of the present invention is to correct the above deficiencies, and provision is made for the direction of the fiber entraining and drawing gaseous currents issuing from the combustion chamber in such a way as to restrain their movement toward the axis of the centrifugal body or even cause their movement away from said axis after the gaseous currents come into contact with and entrain the filaments projected by the centrifuging body. This guidance of or control over the gaseous currents issuing from the combustion chamber may be effected by the use of air or gas currents or mechanical deflection elements located below the centrifugal body.
According to the embodiments of the invention illustrated herein, mechanical deflection elements of conical outline are provided below the centrifugal body to guide the entrained filaments outwardly from below the center of the centrifugal body to prevent the sticking of the filaments therebelow. The deflection effects attained by these elements may be realized by fitting the lower part of the centrifugal body with a truncated cone guide surface. The guide surface may also be independent of the centrifugal body and may be placed below it and assume the form of a fixed conic surface.
In the drawings which illustrate preferred embodiments for executing the invention:
FIG. 1 is a fragmentary vertical section through the centrifugal body and the combustion chamber, showing a frusto-conical apron at the bottom of the centrifugal body for guiding and deflecting the hot gases from the combustion chamber and the fibers entrained the rein and drawn thereby; and
FIG. 2 is a sectional view showing the use of a conical member to induce the spread of the hot gases from the combustion chamber carrying the entrained fibers.
In the illustrated embodiments of the invention, a centrifugal body 1, rotating at high speed about its axis, through appropriate driving means at a speed of 3,000 revolutions per minute, or higher, carries at its peripheral part a cylindrical wall 1b bearing 2 to 20 rows of projection orifices 2 of suitable diameter, through which the molten material is projected at a temperature of about 1300" C.
It is advantageous for the orifices provided in the frontal peripheral wall of the centrifugal body to be sepa rated in such a way that the distances separating the neighboring orifices be about the same. A suitable spacing of the orifices can be made by placing them according to regular quincuncial arrangements. A combustion chamber 3 of general annular shape is provided with an expansion orifice or orifices 4 which delivers the combustion gas at a very high speed and high temperature. The orifice 4 and the wall or walls defining the same are so positioned in respect to the peripheral wall 1b of the centrifugal body and the orifices contained therein that the molten material or filaments, as they are projected from the centrifugal body or at a slight distance therefrom are thrown into and picked up, entrained in and drawn by the hot gases passing across the peripheral surface of the centrifuge wall 1b and at an angle to the normal line of projection of the filaments from the centrifugal body. These hot gases pass lightly over the peripheral wall of the centrifugal body and are in contact with all the projection orifices.
FIG. 1 shows a truncated cone guide surface 8 attached to the centrifugal body. Its generatrix makes a'gamma angle with the axis of the centrifugal body. This gamma angle may be of the order of 10. As a consequence the hot gases with the entrained fibers will be deflected outwardly and away from the axis of the centrifugal body.
FIG. 2 shows a stationary conic element 11 placed below the centrifugal body to produce also the spread of hot gases and the entrained fibers. The conic element may be attached in any convenient manner, for example, by means of a rod 12 placed along the axis of the centrifugal body or it may be supported from below.
In both forms of the invention, the centrifugal body will be heated internally by an appropriate burner or burners (not shown) so as to maintain the molten supply of material passing through the tube and into the interior of the centrifuge in a homogeneous state and at the proper centrifuging temperature.
Likewise in both forms of the invention, the fibers projected from the orifices in the centrifugal body enter but do not pass through or beyond the hot gases issuing from the combustion chamber. Once the fibers enter the ring of hot gases or are picked up by those gases they are entrained the rein and turned downwardly and attenuated and drawn into fine fibers by the travel and traction exerted by those gases. This end will be attained by appropriately adjusting or regulating the centrifugal force and the force of the hot gases issuing from the hot chamber.
What is claimed is:
1. In apparatus for producing glass fibers from thermoplastic vitreous material, the combination of a centrifugal body having a peripheral wall provided with a plurality of superposed rows of orifices therein and adapted to receive at its interior portion a supply of the thermoplastic material in the viscous state, said body being rotatable at a speed sufiicient to project the viscous material outwardly and uniformly through said orifices, a combustion chamber located adjacent said body and provided with a discharge opening having walls shaped to direct the discharge of gases from said chamber at high temperature and high velocity in a ring-like blast across said rows of orifices close to and in light contact with the peripheral wall of said body, said gases travelling at an angle to the plane of rotation of said body whereby said streamlets of viscous material issuing from the orifices of the rotating body are turned, entrained and drawn out by said gases, and means below said centrifugal body for diverting said streamlets outwardly from the center of said centrifugal body comprising a conical element below said centrifugal body with its smaller end nearest said body.
2. An apparatus as set forth in claim 1 wherein said conical element is of frusto-conical outline and is attached to the bottom of said centrifugal body.
3. An apparatus as set forth in claim 1 wherein said conical element is spaced below said centrifugal body co axially therewith.
References Cited in the file of this patent UNITED STATES PATENTS 1,357,206 Fuller Oct. 26, 1920 2,431,205 Slayter Nov. 18, 1947 2,603,833 Stalego July 22, 1952 2,609,566 Slayter Sept. 9, 1952 2,616,124 Lyle Nov. 4, 1952 2,624,912 Heymes Jan. 13, 1953
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