US2861393A

US2861393A - Production of coated-glass fibers

Info

Publication number: US2861393A
Application number: US449182A
Authority: US
Inventors: Harry B Whitehurst; William P Warthen
Original assignee: Owens Corning Fiberglas Corp
Current assignee: Owens Corning
Priority date: 1954-08-11
Filing date: 1954-08-11
Publication date: 1958-11-25
Anticipated expiration: 1975-11-25
Also published as: GB788814A; DE1003924B; FR1133553A

Description

Nov. 25, 1958 H. B. WHlTEHURST E TAL PRODUCTION OF COATED-GLASS FIBERS Filed Aug. 11, 1954 INVENTORS' 44 TTOPNEVEE HAPPY 5 WH/Tf/ll/PST Mil/4M 1- 1422mm States Patent fer-i PRUDUCTIQN 0F CUATED-GLASS FIBERS Harry B. Whitehurst and William P. 'Warthen, Newark,

Ohio, assiguors to Owens-(Zeroing Fiherglas Corporation, a corporation of Delaware Application August 11, 1954, Serial No. 449,182

Claims. (Cl. 49-17) This invention relates to the production of coated, continuous glass fibers, and more particularly to an improved method and means for applying coatings of material to glass fibers in continuous forming operations.

In coating continuous glass fibers with heat-liquifiable coating material as, for example, by the method and means illustrated and described in the copending application Whitehurst et. al., Serial Number 322,598, filed November 26, 1952, it has been found that conditions often arise in the coating operations under which the surface tension and viscosity of the fiuid is so great as to prevent the fibers from becoming enveloped within globules of the fluid material under the usual forces of attenu ation of fibers from a feeder.

Briefly, the method of producing coated glass fibers exemplified by the above mentioned disclosure involves the steps of attenuating molten glass streams into thin continuous fibers drawn in vertical paths through individual or common strip-like globules of the coating material. The fiber paths are arranged to pass over the face of. an applicator unit from which the coating material is emitted. The fluid is suspended in globular form in the fiber paths under its own surface tension but the fibers must first be wet out before they can be drawn under stable operating conditions through the globule. Under certain conditions of surface tension and aflinity of the coating material for glass, however, it becomes difficult to cause the fibers to become wet out in opposition to surface tension of the coating fluid when only the minute forces of attenuation at the feeder are exerted. Difficulty arises in that the projecting, self-supporting globules of material through which the filaments are to be drawn, in extending in a direction generally perpendicular to the paths of the fibers, often push the fibers laterally from their straight line paths because of a lack of tautness therein which would otherwise cause them to remain more fixed in their paths of movement. With tautness established in the fibers, however, they offer resistance to latral movement and tend more readily to become enveloped by the coating fluid.

In view of the foregoing, it is. an object of the present invention to provide a more stable and self-starting meth- 0d and means for producing coated glass fibers.

A more specific object of the invention is to provide a simple means for imparting controllable amounts of tension in. fibers attenuated from feeders and drawn through projecting accumulations of the coating fluid. to affect production of coated-glass fibers.

Stillanother object of the inventionis to provide a more stable production operation for manufacture. of coated-glass. fibers, such as metal-coated glass fibers, without: requiring extensive modification of existing; apparatus to effect the desired results.

In a broad sense, these objectivesare attained according to the; present invention by" exertion of controlled drag forces on the fibers immediately after"; attenuation. and before application of coating fluid in. order to establish the tension forces desired. More particularly, the? con- '2 trolled drag is imparted to establish local tension in the fibers directly at the points where coating fluid is applied.

A feature of the invention is that it enables a self-starting initiation of coating operations where heretofore special care and separate steps to start the coating were necessary. v

A further feature of the invention lies in the fact that while new tension forces are developed in localized portions of the fibers, the total tension in the fibers may actually be lessened in certain particular arrangements for exertion of drag described herein.

Other objects and features of the invention will become apparent from the following description taken in conjunction with the drawing, in which:

Figures 1 and 2 are front and side-elevational views, respectively, for producing metal-coated glass fibers in which the desired controlled tension in the fibers at the point of application of coating metal is produced by a tension bar or rod contacting the fibers at points above those where molten metal is fed to the fibers;

Figure 3 shows an alternative arrangement for positioning a tension bar in engagement with the fibers above the points where coating material is supplied;

Figure 4 is an enlarged view of a portion of the arrangement of Figure 3 showing with greater clarity the association of the fibers with the tensioning bar and applicator face.

Figure 5 shows still another embodiment of the invention in which pneumatic blowers are arranged to establish fiber tension by directing blasts of gas against the fibers at points above the coating applicator;

Figure 6 shows an applicator for supplying metal coatings to a single row of. glass fibers in which the tension in the fibers is produced by providing a special tensioning surface built into the outlet portion of the metal applicator; and

Figure 7 shows an applicator somewhat like that of Figure 5 for coating 21' double row of glass fibers attenuated from a feeder.

While the invention is herein described with reference to application of metal to glass fibers, it will be under.- stood that the principles have broader connotation and can be applied to coating operations involving other materials as Well.

Referring to the drawings in greater detail, Figures 1 and 2 show a general layout of apparatus for producing metal-coated glass fibers in which molten glass is supplied inthe form of streams from a bushing or feeder 11. associated with a source of molten glass such as a glass-melting oven 10. The molten streams are supplied from feeder orifices 12' and" are attenuated into fibers 13 by forces exerted by a winder 21 which draws the fibers in spacedrelationship over the face of a metalapplicator unit 14 and in engagement with a size applicator roll 18 before being gathered into a strand 19 over a grooved spinner-type gathering member 20..

The spinner-type gatherer 20 is made ofnon-abrasive material such as graphite or Teflon and is arranged tobe rotatable in order todistribute the wear over the gathering member and to reduce the frictional forces exerted on the fibers drawn thereover. The coated fibers are gathered into a strand'19which' is collected into package form on a tube'23 driven by a. collet of the Wlfidf 21'. A traversing mechanism such as a spiral-wire type traverse 22 having two or more spiral configurated' wire traversing. arms moves the strand back and forth across the width of the package" on the tube 23 to form apackageof predetermined size.

Molten metal is emitted from the orifice 16 ofthe applicator 14: and projects: in: suspended relationship from the orifice in the path: of the fibers 1*3'being; attenuated from the orifices 12. The metal is suspended by its own surface tension in the form of a longitudinal strip-like globule after passage through a channel extending between the applicator face and the reservoir of the applicator 14. On passage of the filaments through the suspended globule, a layer of the metal taken from the globule is coated on the fibers and subsequently becomes solidified into an integrally associated coating on the fibers.

In having appreciable surface tension, the molten globule 15 offers a resistance to introduction of fibers. This resistance must be overcome by pushing the filaments below the surface in order to initiate coating operations. It has been found, however, that if sufiicient tautness is established in the fibers at the points of application of molten metal, and the applicator is moved into position Where the molten globule is suspended inmediately in the path through which the filaments are passed, then the force of tension acts to prevent lateral movement of the fibers, and accordingly the fibers become self-embedding. This principle is utilized in the present invention to provide a simple method and means whereby a self-initiation of coating operations can be accomplished without need for modification of basic fiber forming principles.

The tension in the portion of the fibers between the feeder outlets and the points of application of metal at the applicator face are usually extremely minute because the longitudinal forces of attenuation in this portion, as provided by the winder, act against only normal air drag on the surfaces of the fibers and the small opposition offered by tension in the molten streams emitted from the orifices 12. For this reason, fibers were required to be manually pushed into the globules of metal through which they were to be passed, and they often, in effect, jumped out of the metal at the face by reason of vibrations such as were frequently developed by external sources. Attempts to reinsert such fibers in the accumulation of metal by exertion of greater tension on the fibers at points below the applicator, resulted in little or no effect since the resisting forces at the feeder did not increase correspondingly. With little tension existing in the fibers on passage over the face of a metal applicator, little or practically no lateral component of force is developed to oppose the surface tension of the molten metal to cause an insertion of the fibers below 'the surface thereof.

According to the present invention, therefore, a fiberengaging drag surface is arranged to extend across the width of the fan of spaced fibers to establish tension within the fibers at the points therein where the fibers pass through the molten globules. In the embodiment of Figures 1 and 2, the drag surface is provided in the form of a longitudinal bar 25 pivotally disposed in contact with the fibers above the applicator 14. The bar is made of non-abrasive material such as graphite and is provided with sufiicient contact surface in engagement with the fibers to establish drag or resistance to movement of fibers thereover, thereby providing the desired amount of tension in the fibers at the points of application of metal. In other words, engagement of the bar with the fibers, in offering resistance to passage of fibers 'thereover acts to establish upward forces in the fibers at points above the applicator face which oppose the action of the winder in drawing the fibers over the metal applicator 14 as well as the size applicator 18 and the gathering member 20.

' It should be noted, as shown in Figures 1 and 2, that the bar 25 need not be in a position to push the filaments below the surface of the globule of molten metal, but can be on the same side of the filaments as the applicator from which the molten metal is emitted. This arrangement develops tension in the fibers and establishes a condition such that sufficient tautness exists in the fibers to assure that the fibers will be forced into the accumulation of metal fed thereto regardless of the surface tension of the metal or other resistance of the metal to initially wet out the fibers. Additionally, with the presence of the tension bar, the path of the fibers can be better controlled and made such that the fibers can pass directly through the center of the accumulation of metal at the face rather than making contact with the face.

In this respect, the pivotable tension bar is provided with a curvilinear surface capable of various degrees of linear contact and tension-establishing relationship with the fibers, thereby permitting a desired degree of tension to be imparted to the fibers and providing a control by which tension may be limited before breakage of the fibers and consequent interruption in operation by excessive tensile stress occurs. The arrangement is also such that vibratory forces developed in the fibers at the point of application of metal are minimized or dampened out by the presence of the bar 25. In enabling the fibers to be drawn through the coating accumulation without need for contact with the face of the applicator itself, it should be noted that the total tension in the fibers can actually be reduced somewhat by the presence of the tensioning bar. This condition arises when the tension developed by the bar above the applicator 14 is less than that which would be developed in the fibers below the applicator by engagement of the fibers with the applicator face.

Figure 3 shows an arrangement wherein a pivotable tensioning bar is located on the side of the fibers 33 opposite to that on which the coating applicator 34 is located. In this arrangement, it is to be noted that the tensioning bar may be utilized to push the contacted fibers into engagement with the face of the metal applicator, if desired. In other respects, however, the tensioning bar functions in a manner identical to that of the embodiment of Figures 1 and 2 in establishing frictional engagement of the bar with the fibers to establish tension in the lengths thereof below the bar. Tautness for positive embedment of the fibers within the molten accumulation or globule of metal from the face of the applicator is thus provided.

Figure 4 shows in greater detail the tensioning bar 35 of the arrangement in Figure 3 illustrating with greater clarity the relationship of such bars with the fibers and applicator face. The bar is provided with a surface having a curvilinear profile permitting varying degrees of frictional engagement with the fibers on being rotated about its pivot 36 for adjustment in final position. Thus, the bar may be rotationally adjusted in position to provide any of a range of drag forces or tension conditions in the fibers permitting selection of the proper drag or tension corresponding to specific coating conditions confronted. The lateral positioning of the fibers determining the path of the fibers through the globule of coating metal also can be readily determined by adjusting the bar about its pivot axis.

Figure 5 shows another arrangement embodying the principles of the present invention in which the glass fibers 43 emitted from a feeder 41 are provided with a tensioning drag by pneumatic blowers 45 disposed on opposite sides of the filaments at locations above the metal applicator 44. The blowers 45 are each provided with a slot orifice from which air directed against the filaments is emitted under such a pressure as to form a plane of air moving in the direction of the filaments to assure that each will offer some resistance to longitudinal movement which must be opposed before the fibers are passed over the applicator. The opposed blowers are inclined slightly upward or downward in being directed to the filaments, in order to prevent each of the blowers from blocking the stream of gas emitted from the other. In this arrangement the gas emitted from the blowers, if desired, can be arranged to cool and thereby aid in determining the thermal history and consequent strength properties of the glass fibers in addition to merely offering resistance to movement thereof.

Figure 6 shows a new type of metal applicator in which the fiber tensioning surface engaging the fibers to establish the tautness desired in the fibers is built directly into the face of the applicator itself. The molten metal emitted from the applicator 44 is passed through a channel 57 to the orifice or orifices from which the metal projects in the path of filaments 53 making contact with the upper lip 55 of the applicator face. Thus, the fibers 53 formed of the glass emitted from the feeder 51 are caused to engage the upper lip 55 which causes the drag in the portion of the filaments passing through the accumulation emitted from the channel 57. The upper lip 55 is accordingly provided with a contact surface of sufiiciently large dimension to establish the drag necessary for stability on passage of the fibers through the molten accumulation. The lower lip 56 is correspondingly made only suificiently large to cause the accumulation to project from the orifice to an extent assuring envelopment of the filaments.

Figure 7 shows still another metal applicator arrangement embodying the principles of the invention and incorporating a tensioning drag surface in the upper lip thereof, but in this instance, the applicator is designed to coat more than one row of fibers emitted from a bushing emitted from a feeder 61. The glass emitted from the feeder is supplied from orifices 62 in spaced rows on the underside of the feeder. On passage over the face of the applicator 64, however, the fibers are arranged to pass in spaced single row relationship in engagement with the upper lip 65 of the applicator. The angle of the path of fibers passed over the face is slightly greater than that of the angle of the arrangement in Figure 6, since the two rows of fibers are in a sense gathered into a single row relationship by the applicator. Thus, a slightly greater overhang of the feeder 61 is required with respect to the applicator face. The molten metal contained in the applicator 64 is supplied through a channel 67 which feeds the metal through an orifice or orifices in the face of the applicator and in projected relationship with respect to the path of the filaments to be coated. The lower lip 66 of the applicator face is correspondingly matched to merely project the metal in desired relationship with respect to the filaments to assure full envelopment thereof.

In both arrangements of Figures 6 and 7, it should be noted that the lower lip may be made to contact the fibers with only a slight degree of pressure so as to effect a wiping of excesses of metal from the fibers after they have been drawn through the major portion of the molten metal. In this sense, the lower lip acts somewhat as a metering member. Further, the upper lip dimension is made such that for a given set of conditions of application of metal to the glass fibers, the area contacted by each fiber is sufficiently large to provide the drag or tensioning forces required to' effect the degree of stability for self-initiation of the coating operation. Again, it should be considered that without the drag resisting force being imparted to the filaments at points above the space where the metal is fed to the fibers, the tension in the portions of the fibers passing through the accumulations of coating material would in many instances be insufiicient to permit reliance on continuity of operation because of the likelihood that surface tension values and vibration might cause the filaments to jump, or to be pushed, out of the coating accumulation.

It will be understood from the foregoing that, while we have shown certain particular forms of our invention, we do not wish to be limited thereto since many modifications may be made within the concepts of the invention and we, therefore, contemplate the appended claims to cover all such modifications which fall within the true spirit and scope of our invention.

We claim:

1. Apparatus for producing continuous, coated glass fibers com rising a feeder supplying streams of molten glass from a source of molten glass, attenuating means arranged to attenuate said streams into continuous glass fibers, coating means having an applicator face laterally disposed with respect to said fibers and across which said fibers are drawn for a coating of material, and force-applying means in direct contact with said fibers between said feeder and coating means acting to increase the tension in the portions of said fibers passing over said face.

2. Apparatus for producing continuous coated glass fibers comprising a feeder supplying streams of molten glass from a. source of molten glass, attenuating means arranged to attenuate said streams into continuous fibers, coating means having an applicator face laterally disposed with respect to said fibers and across which said fibers are drawn for a coating of material, and forceapplying means acting on said fibers between said feeder and said coating means to increase the tension in the portions of said fibers passing across said face, said forceapplying means comprising a member laterally disposed with respect to the paths of said fibers and arranged to make frictional engagement with said fibers individually.

3. Apparatus for producing continuous coated glass fibers comprising a feeder supplying streams of molten glass from a source of molten glass, attenuating means arranged to attenuate said streams into continuous fibers, coating means having an applicator face laterally disposed with respect to said fibers and across which said fibers are drawn for a coating of material, and forceapplying means acting on said fibers between said feeder and said coating means to increase the tension in the portions of said fibers passing across said face, said forceapplying meansv comprising a member laterally disposed and making frictional engagement with said fibers individually on the same side of said fibers as that on which said applicator face is disposed.

4. Apparatus for producing continuous coated glass fibers comprising a feeder supplying streams f molten glass from a source of molten glass, attenuating means arranged to attenuate said streams into continuous fibers, coating means comprising an applicator face laterally disposed with respect to said fibers and across which said fibers are drawn for a coating of material, and forceapplying means acting on said fibers between said feeder and said coating means to increase the tension in the portions of said fibers passing across said face, said forceapplying means comprising a member laterally disposed and making frictional engagement with said fibers individually on the opposite side of said fibers from that on which said applicator face is disposed.

5. Apparatus for producing continuous coated glass fibers comprising a feeder supplying streams of molten glass from a source of molten glass, attenuating means arranged to attenuate said streams into continuous fibers, coating means for supplying coating material having an applicator face laterally disposed with respect to said fibers and across which said fibers are drawn for a coating of material, and force-applying means acting on said fibers between said feeder and said coating means to increase the tension in the portions of said fibers passing across said face, said force-applying means comprising a member laterally disposed with respect to the paths of said fibers and in direct contacting engagement with said fibers, said force applying means also having associated positioning means for positioning said member for various lengths of contact with each of said fibers to permit selective establishment of a controlled degree of frictional engagement with each of said fibers for the degree of tension desired in the fibers at said face.

6. Apparatus for producing continuous coated glass fibers comprising a feeder supplying streams of molten glass from a source of molten glass, attenuating means arranged to attenuate said streams into continuous fibers, coating means having an applicator face laterally disposed with respect to said fibers and across which Said 7 fibers are drawn for a coating of material, and force-applying means acting on said fibers ahead of said coating means to increase the tension in the portion of said fibers passing across said face, said force-applying means comprising a member having a graphite surface arranged to make frictional engagement with said fibers.

7. Apparatus for producing continuous coated glass fibers comprising a feeder supplying streams of molten glass from a source of molten glass, attenuating means arranged to attenuate said streams into continuous fibers, coating means having an applicator face laterally disposed with respect to said fibers and across which said fibers are drawn for a coating of material, and force-applying means acting on said fibers to increase the tension in the portions of said fibers passing across said face, said force-applying means comprising a surface of preselected area in direct contacting frictional engagement with each of said fibers at the leading edge of said face to establish a tension of predetermined degree in each of said fiber portions.

8. Apparatus for producing continuous metal coated glass fibers comprising a feeder supplying streams of molten glass from a source of molten glass, attenuating means arranged to attenuate said streams into continuous fibers, metal coating means having an applicator face laterally disposed with respect to said fibers and across which said fibers are drawn for a coating of metal, and force-applying means acting on said fibers to increase the tension in the portions of said fibers passing across said face, said face having an orifice therein extending across the paths of said fibers and from which molten metal coated on said fibers is supplied, said force-applying means comprising a surface of preselected area making frictional engagement with each of said fibers before said fibers pass across said orifice,

9. The method of producing a glass textile strand which comprises simultaneously and continuously drawing a multiplicity of fine glass fibers from a supply body of molten glass, continuously winding the filaments in strand form into a package, simultaneously and continuously grouping the filaments at a point between said supply and package in the form of a strand with the filaments substantially parallel in the strand, frictionally engaging each of said filaments individually with a contact surface ahead of said point to increase tension in said fibers following the portions engaged, and coating the filaments with molten metal after said engaged portions but ahead of said point to provide an individual coating for each.

10. Apparatus for producing continuous coated fibers of heat-softenable material comprising a feeder supplying streams of molten material from a source of molten fiber forming material, attenuating means arranged to attenuate said streams into continuous fibers, coating means having an applicator face disposed for passage of said fibers thereacross for a coating of material as they are drawn by said attenuating means, and force-applying means in direct contact With said fibers and acting on said fibers before said coating means to increase the tension in the portions of said fibers passing across said face.

References Cited in the file of this patent UNITED STATES PATENTS 1,496,309 Girvin June 3, 1924 2,234,986 Slayter et al Mar. 18, 1941 2,373,078 Kleist Apr. 3, 1945 2,571,025 Fletcher Oct. 9, 1951 FOREIGN PATENTS 840,209 France Jan. 11, 1939