US3254978A

US3254978A - Method and apparatus for forming fibers

Info

Publication number: US3254978A
Application number: US438676A
Authority: US
Inventors: Guillermo D Hayes
Original assignee: Pittsburgh Plate Glass Co
Current assignee: PPG Industries Inc
Priority date: 1965-03-10
Filing date: 1965-03-10
Publication date: 1966-06-07
Anticipated expiration: 1983-06-07

Description

June 7, 1966 G. D. HAYES 3,254,978

METHOD AND APPARATUS FOR FORMING FIBERS Original Filed March 10. 1961 H mm GUILLERMO D. HAYES 40 BY Q'sA-QWN gun F 3 ATTORNEYS United States Patent This application is a continuation of my copending application Serial No. 94,764, now abandoned, filed March 10, 1961, and entitled, Method and Apparatus for Forming Fibers.

This invention relates to a method and apparatus for forming and winding strands and it has particular relation to a method and apparatus for forming a plurality of glass fiber strands and winding them on a single forming tube. The invention will hereinafter be described -with respect to the formation of glass fiber strands, but

is is to be understood that it is applicable to the winding of strands of other types of materials.

In the production of continuous filament glass fiber strand, a number of individual glass filaments are drawn from an electrically heated, platinum alloy bushing containing a molten supply of the glass. The glass passes through tips which define orifices in the bottom of the bus-hing and forms inverted cones of glass suspended from the ends of the tips. The individual filaments are drawn from the cones of glass at a high rate of speed, i.e., 5,000 to 20,000 feet per minute, and are grouped into a strand as they pass over a suitable guide. The strand is thereafter wound on a rapidly rotating forming tube.

There is no twist in the strand as it is thus formed,

and a size composed of a binder and a lubricant, such as starch and a vegetable oil, is applied to the individual filaments prior to the time they are grouped into the strand and wound on the tube in order to bond them together and maintain the integrity. of the strand. The strand is wound on the tube with a slight traverse so that succeeding turns cross each other at an angle rather than parallel to each other so the strand can be Patent No. 2,386,158 and Belgian Patent No. 507,587 to.

separate the filaments into groups of filaments and combine the filaments in each group in order to form a plurality of strands and then wind the strands simultaneously on a single forming tube. The process of the Belgian patent differs from the process of the US. patent in that the traverse of US. Patent No. 2,391,870 is used in place of the pinwheel-type traverse of US. Patent No. 2,386,158.

In each of the prior art processes mentioned above the spacing of the strands from each other differs from place to place as they are laid down on the forming package since the traversing mechanisms exert different tensions on the strands from point to point along their lengths as they pass over the traversing mechanisms. The spacing of the strands from each other on the forming package may vary from one extreme Where the strands overlap each other to the other extreme where they are quite far apart, for example about 1 to 2 inches. If the strands are too far apart on the forming tube, they do not-unwind evenly from the inside of the forming package and bird nesting may result. Bird nest- -of the furnace.

3,254,978 Patented June 7, 1966 ing is the pulling off from the inside of the package of many turns of strand at once, rather than a single turn at a time. When this occurs, the strands break and the unwinding operation is interrupted. It is exceedingly difficult to untangle the bird nests and find the ends of the strands so that the unwinding may be restarted. It is therefore desired .that the strands be laid down on the forming tube in more closely spaced relation toeach other.

In accordance with the present invention, it has been found that the winding of a plurality of strands on a single forming tube by means of a traverse that constantly varies the spacing between the strands can be accomplished without encountering the defects of the prior art if the spacing of the strands is controlled by suitable guide members located strategically between the strand gathering shoes and the traversing mechanism.

ice

The guide members group-the strands closely together but maintain them separate as they approach the traversing mechanism, and this tends to even out the differences in tension and reduce the'maximu-m spacing between the strands as they are traversed and wound on the forming tube.

The invention can be further understood by reference to the following description of the drawing in which:

FIG. 1 is an elevation of a glass fiber forming process utilizing the present invention;

FIG. 2 is aside view of FIG. 1;

FIG. 3 is a plan view of a guide which is suitable for use in the practice of the invention;

FIGS. 4 and 5 are diagrammatic views of the positions of the strands as they pass through the guide illustrated in FIG. 3 on their way to the traversing mechanism and forming tube; and

FIG. 6 is a side elevation illustrating the manner of mounting the guide.

In FIGS. 1 and 2 of the drawing there is shown a glass melting furance or forehearth thereof 10 containing a supply of molten glass 11 and having an electrically heated, platinum alloy bushing 13 attached to the bottom The bushing is provided with a series of orifices in the form of tips 14 through which the molten glass flows and forms in small inverted cones 15 suspended from the bottoms of the tips 14. The tips are usually formed in a number of rows, for example 4 to 20 or more rows, having a great many tips in each row so that the total number of tips is about 200 to 400 or more in number. The bushing is thus rectangular in shape with the long dimension facing the operator and being at right angles to the axis of a forming tube 17 mounted on winder support 18.

Glass filaments 16 are pulled from the cones of glass 15 at a very high rate of speed, i.e., 5,000 to 20,000 feet per minute, and wound on the rapidly rotating forming tube 17. The glass filaments are grouped into two separate strands 19 as they pass over two separate gathering shoes 20 prior to their being Wound on the tube 17. The inven tion is not limited to formation of two strands, and it is to be understood that more than two strands can be formed and wound on a single forming tube. The shoes 20' are centered below the bushing and are in a vertical plane and a horizontal line which are parallel to the long dimension of the bushing running through the center of the bushing. Usually, a size containing a liquid binder and a lubricant, such as a combination of starch and vegetable oil, are applied to the individual filaments prior to the time they grouped in the strands. The size is applied to the filaments by passing them over rotating rolls 25 which are mounted for rotation in reservoirs 27 containing the size.

As the strands 19 are wound on the tube 17, they are rapidly traversed by traverse 30. The traverse 30 is a spiral wire traverse as shown in US. Patent No. 2,391,870. It has a pair of conical, spiral, wire earns 32 mounted on a shaft 33. The major diameter of each cam is opposite to and overlaps the minor diameter of the other cam. The shaft 33 or axis of the traverse is mounted parallel to the axis of the forming tube and the traverse 30 is rotated very rapidly about its axis to provide the traversing motion to the strands.

In operation, the pair of conical, spiral, wire cams alternately engage the strands and cause them to be moved positively along a portion of the length of the forming tube and returned by successive engagement of the strands with the cams. As the strands reach the end or minor diameter of one cam, they overlap each other. Their motion in the direction urged by this cam is interrupted by the strands being engaged by the major diameter of the other cam and they are immediately started on their return movement to the other or major diameterend of the other cam. The points at which the strands lay down on the forming tube are determined by the distance between the strands as they cross over-the cam surfaces, the tension on the strands as created by the forming tube speed, the weight of the strands and their angle of approach to the traverse, traverse speed and the side motion the traverse exerts against the strand, i.e., the angularity of the traverse cams to the traverse spindle.

During this movement along the cam from the end of one cam to the end of another according to the prior art process, the strands became separated to too great an extent on the traverse and consequently on the forming package to permit their even unwinding from the forming package. Even though the strands can be led from gathering shoes such as shoes which are mounted in a plane which is perpendicular to the axes of the traverse and forming tube, the lead angle of the spiral cams caused the strands to be laid on the forming tube in greater spaced relation than desired. This was caused by the fact that the cams contacted one strand before the other as they passed over the cams on the traverse. This is because the strands approach the traverse from different angles as they pass across the traverse on their trip from the gathering shoes to the forming tube. The different angles cause one strand to lead or lag the other strand substantially depending upon the particular position of the strands on the earns 32 of the rotating traverse 30. In the prior art the difference in angle of approach of the strands to the traverse was great enough to cause the strands to be unduly spaced on the forming package for proper unwinding.

In accordance with the present invention, the individual strands are caused to change direction between the shoes 20 and traverse 30 so that they approach the traverse in a more nearly parallel, spaced relation to each other than when they travel in a straight line between the shoes 20 and traverse 30'. This reduces the undesirable large spacing of the strands as they approach the traverse and as they are deposited on the forming tube.

This is accomplished by means of guide 36 which is placed intermediate the shoes 20 and the traverse 30. The action of the guide 36 is to control the point of tangency in the strands contact with the forming tube. The points of tangency are brought very close together, but distinctly separated during the central portion of their traverse in each direction. The dimensions of the strand guide 36 are chosen so that these points of tangency are approximately to A inch apart at the widest point, preferably about inch. The strands overlap each other at the ends of each traverse as the lead strand crosses over the other strand.

The guide 36 consists essentially of four spaced parallel guiding surfaces which are mounted with their long dimensions being parallel to each other and to the axis of the forming tube 18 and traverse 30. The surfaces may be in the form of bars or

wires

38, 39 and 40 as illustrated in FIG. 3. The

bars

38 and 40 extend out parallel to each other from a supporting member 42 and at a certain distance therefrom they make a smooth curve and return to the support at an angle of about 75 degrees. The

bars

38 and 40 act as grouping bars to bring the strands together. Intermediate the

bars

38 and 40 is a separating bar 39. The diameter of the bar 39 may be about A; to inch. The bars are spaced from each other approximately to /s of an inch, and the guiding surfaces of bars 38 and 40' are about A to inch apart.

The distance between the shoes 20 and the traverse determines the structure of the guide 36 which can be used. For example, there is present in commercial manufacturing processes both a single and a double level process. In the single level process, the shoes 26 are about 26 inches away from the traverse 30; whereas in the double level process the shoes 20 are about 88 inches away from the traverse 30. In both of these operations the strands 19 are spaced from each other about 2 to 3 inches as they cross over the shoes 20. Also in both of these operations the guide 36 is mounted about 12 inches above the traverse 30. The guide 36 illustrated in FIG. 3 can be employed in both the single and double level processes.

The tensions in the strands as they pass through the guide are greater in the single level process because of the sharper angles of travel involved. FIGS. 4 and 5 illustrate how the strands 19 bend over the

bars

38, 39 and depending upon whether they are being contacted by the major diameter or minor diameter of the spiral cams 32. In FIG. 4 the strands 19 are shown as being engaged by the major diameter of one of the earns 32. They are bent around bars 38 and 39 which hold them in closely spaced relation. In FIG. 5 the strands 19 are shown as being engaged by the minor diameter of one of the cams 32. In

this case, the strands bend around bars 39 and 40 and are kept in closely spaced relation. With this reduced and relatively small spacing of the strands as they approach the traverse it is possible to keep the distance between the strands to a controlled minimum as they are laid down on the forming tube. They can then be readily unwound without the difiiculties previously encountered.

In the double level process, the strands do not have as much tension exerted on them because the angles of travel of the filaments from the bushing to the forming tube are not as severe. It has been found that the center bar 39 can be eliminated from the guide 36 and beneficial results can be obtained. In the double level process the guide 36 is primarly necessary as a grouping guide and the central dividing bar 39 is optional. For best results, however, the dividing bar should be included.

It can be seen that in both of these processes the changes in direction of the strands by the guide 36 differ repeatedly as the traverse rotates and the strands move in and out on the traverse cam surfaces. However, the guide 36 is designed so that it limits the changes in direction of the strands so that they are always closer together at the point where they pass over the guide 36 than they would be if the guide was not employed.

The mounting of the guide 36 is shown in FIG. 6. The support 42 is mounted on extension 44 which pivots through integrally attached rods 46 which are mounted for rotation in bearings 50 which are rigidly mounted on the support for the winder. The rods 46 are cylindrical and are free to rotate through a defined arc to permit the guide to be rotated upwardly from its horizontal position to a vertical position. A lug 52 mounted on the support 53 for the extension 44 limits the movement of the extension 53. This mounting of the guide 36 permits the guide to be moved from its horizontal-position for normal use to a vertical position where it is out of the way of the strand path. This is desirable when the fiber forming equipment is used in the manufacture of a single strand.

'Although the present invention has been described with respect to specific details of certain embodiments thereof, it is not intended that such details serve as limitations upon the scope of the invention except as set forth in the following claims.

I claim:

1. In the method of forming a plurality of strands which comprises drawing a multiplicity of individual filaments from a molten, thermoplastic body, grouping the filaments together at spaced points in a given plane to form a plurality of laterally spaced strands, advancing the spaced strands in converging straight line paths to a traversing station and then to a winding tube, winding the strands on the tube in spaced relation to each other and traversing the strands in directions perpendicular to said given plane as they are wound on the tube, the traversing serving to impart different amounts of tension on the different strands and deposit the strands on the tube in varying spaced relation to each other, with the strands periodically overlapping each other and periodically being widely spaced from each other, the improvement which comprises modifying the straight line path of at least one of the strands to decrease the angle of convergence of said strands with one another while retaining a spacing therebetween prior to subjecting the strands to the traversing action, said modification minimizing the difference in tension exerted on the spaced strands during the traversing action and reducing the normal spacing of the strands as they are wound on the tube.

2. Apparatus for forming strands which comprises a bushing for containing a supply of thermoplastic material and means for drawing a multiplicity of individual filaof convergence of said strands to group them closer together while maintaining them in a slightly spaced relation to the traversing element.

3. Apparatus as described in claim 2 wherein the traversing element is composed of a spindle mounted parallel to the axis of the winding tube and having spiral, conical,

opposed cams mounted on it so that the minor diameter of one cam is opposed to the major diameter of the other cam for each pair of cams.

4. Apparatus as described in claim 2 wherein the guide means includes another guiding surface means positioned between said spaced guiding surfaces.

References Cited by the Examiner UNITED STATES PATENTS 2,386,158 10/1945 Collins 24242 2,391,870 1/1946 Beach 24243 3,072,518 1/1963 White 161-173 X DONALL H. SYLVESTER, Primary Examiner.

ments from the bushing, forming them into strands and R. L. LINDSAY, Assistant Examiner.

winding them on a tube, said means including a winding

Claims

1. THE METHOD OF FORMING A PLURALITY OF STRANDS WHICH COMPRISES DRAWING A MULTIPLICITY OF INDIVIDUAL FILAMENTS FROM A MOLTEN, THERMOPLASTIC BODY, GROUPING THE FILAMENTS TOGETHER AT SPACED POINTS IN A GIVEN PLANE TO FORM A PLURALITY OF LATERIALLY SPACED STRANDS, ADVANCING THE SPACED STRANDS IN COVERGING STRAIGHT LINE PATHS TO A TRAVERSING STATION AND THEN TO A WINDING TUBE, WINDING THE STRANDS ON THE TUBE IN SPACED RELATION TO EACH OTHER AND TRAVERSING THE STRANDS IN DIRECTIONS PERPENDICULAR TO SAID GIVEN PLANE AS THEY ARE WOUND ON THE TUBE, THE TRANVERSING SERVING TO IMPART DIFFERENT AMOUNTS OF TENSION ON THE DIFFERENT STRANDS AND DEPOSIT THE STRANDS ON THE TUBE IN VARYING SPACED RELATION TO EACH OTHER, WITH THE STRANDS PERIODICALLY OVERLAPPING EACH OTHER AND PERIODICALLY BEING WIDELY SPACED FROM EACH OTHER, THE IMPROVEMENT WHICH COMPRISES MODIFYING THE STRAIGHT LINE PATH OF AT LEAST ONE OF THE STRANDS TO DECREASE THE ANGLE OF CONVERGENCE OF SAID STRANDS WITH ONE ANOTHER WHILE RETAINING A SPACING THEREBETWEEN PRIOR TO SUBJECTING THE STRANDS TO THE TRAVERSING ACTION, SAID MODIFICATION MINIMIZING THE DIFFERENCE IN TENSION EXERTED ON THE SPACED STRANDS DURING THE TRAVERSING ACTION AND REDUCING THE NORMAL SPACING OF THE STRANDS AS THEY ARE WOUND ON THE TUBE.

2. APPARATUS FOR FORMING STRANDS WHICH COMPRISES A BUSHING FOR CONTAINING A SUPPLY OF THERMOPLASTIC MATERIAL AND MEANS FOR DRAWING A MULITIPLICITY OF INDIVIDUAL FILAMENTS FROM THE BUSHING, FORMING THEM INTO STRANDS AND WINDING THEM ON A TUBE, SAID MEANS INCLUDING A WINDING TUBE, A PLURALITY OF LATERALLY SPACED GATHERING SHOES IN A GIVEN PLANE FOR GATHERING THE FILAMENTS INTO A PLURALITY OF STRANDS, A CAM TRAVERSING MEANS TRAVERSING SAID STRANDS ALONG SAID TUBE IN THE DIRECTION PERPENDICULAR TO SAID PLANE AND EXERTING DIFFERING AMOUNTS OF TENSION ON THE STRANDS AS THEY AS TRAVERSED AND WOUND ON THE WINDING TUBE, AND A GUIDE MEANS INTERMEDIATE THE GATHERING SHOES AND TRAVERSING ELEMENT, SAID GUIDE MEANS DECREASING THE ANGLE OF CONVERGENCE OF SAID STRANDS TO GROUP THEM CLOSER TOGETHER WHILE MAINTAINING THEM IN A SLIGHTLY SPACED RELATION TO THE TRAVERSING ELEMENT.