IMPROVED LINE ACCUMULATING DEVICE

Abstract: A device for accumulating a thin fiber, such as an optical fiber. Line accumulating members are provided around which a fiber is drawn and wound. The fiber is diverted from its path by a plurality of guide wheels, one or more of which are attached to a shaft which causes the guide wheels to rotate about the line accumulating mem­ bers. At the same time, the guide wheels which wind the fiber are caused to move laterally relative to the line accu­ mulating members to evenly distribute the fiber around the line accumulating members. This is accomplished by mechanically coupling the assembly for laterally moving the guide wheels to the assembly which rotates them about the line accumulating members. The device is designed to ac­ complish this while the line accumulating members are fixed to the body of the device. This results in a line accu­ mulating device which is compact and simple.

Description: IMPROVED LINE ACCUMULATING DEVICE BACKGROUND OF THE INVENTION This invention relates to a device for accumulating thin fibers, particularly optical fibers. When, for example in an optical fiber drawing line, an optical fiber is broken at a tension tester located between the line drawing machine and a winding unit, it becomes necessary to reattach the optical fiber to the bobbin of the winding unit. In order to prevent interruption of operation of the line drawing machine, it is necessary to provide a line accumulating device between the tension tester and the line drawing machine. In most optical fiber drawing operations which are carried out at a high speed, it is important that the tension of the fiber being drawn remain fairly constant while the fiber is accumulated It is also beneficial that the device provide a large amount of accumulation while requiring little floor space in a production facility. The present invention specifically relates to an improvement of a line accumulating device of a type described in Japanese Utility Model Application No. 6794/1982 filed January 18, 1982. The line accumulating device of the present invention is small in size while providing large accumulation capacity. The device described in the above-referenced Japanese Utility Model Application is described below with reference to Figs. 1, 2 and 3. SUMMARY OF THE INVENTION In the improved line accumulating device according to the invention, lateral movement of line accumulating guide roller groups is eliminated by moving laterally the fiber distributing guide wheels relative to the guide roller groups. To facilitate such movement, the guide roller group sliding mechanisms which are essential in the device described in the above-referenced utility model application are eliminated and, the distributing guide wheels are made to slide laterally along the length of the bar which rotates the guide wheels around the line accumulating guide roller groups to wind the fiber. This improvement in design makes it possible to considerably reduce the size of the line accumulating device. The invention is advantageous in that it takes little space and can easily be added to presently installed equipment for producing optical fibers. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a front view of an embodiment of a conventional line accumulating device; Fig. 2 is a sectional view taken along line A-A in Fig. 1, showing how a line is wound around the guide roller group; Fig. 3 is a side view of a guide roller group in detail; Fig. 4 shows a front view of an embodiment of an improved line accumulating device; Fig. 5 shows a detail of a guide wheel mounted on a bar designated part C in Fig. 4; and Fig. 6 shows a sectional view taken along the line B-B in Fig. 4. DESCRIPTION OF THE PREFERRED EMBODIMENT Fig. 1 is a front view of a fiber winding type line accumulating device as described in the abovereferenced utility model application, and Figs. 2 and 3 show the fiber winding section of the device in detail. An optical fiber 1 moves in the direction of the arrows "a." The device has line accumulating guide rollers 2 shaped with a number of ring grooves 3 cut into the outer wall of each guide roller 2 at predetermined intervals "P". Each guide roller 2 is rotatably mounted through bearings 4 on a shaft 5. A plurality of shafts 5 are fixedly secured between side plates 6, 6', 7 and 7' in such a manner that their ends are arranged in a circle at equal intervals on the circumference thereof. Accordingly, a plurality of guide rollers 2 are arranged in such a manner that their ends form a circle spaced at equal intervals on the same circumference. As shown in Fig. 3, the guide rollers 2, 2' and 2" are so arranged from one another such that their grooves 3 are shifted in the axial direction. Specifically, the grooves 3 of the guide rollers 2, 2' and 2" are shifted by a distance "sus' in the axial direction from one another. The dis- tance "S" is equal to the distance "P" divided by the number of guide rollers 2 on the circumference, "n", (S=P/n). The device contains two such groups of guide rollers 2 which as shown in Fig. 1 confront each other. The side plates 7 and 7' which support the groups of guide rollers are fixedly secured to bases 8 and 8', respectively. The bases 8 and 8' are engaged through slides 25 and 25' to a fixed guide bar 24. The slides 25, 25' move along guide bar 24 to laterally move the bases 8, 8' which are fixedly secured to the slides 25, 25'. Guide wheels 26 and 26' which direct a fiber from a line drawing machine and away toward the tension tester are secured to the bases 8 and 8', respectively. The device further includes a shaft 12 which extends along the central axis of one of the groups of guide rollers as shown in Fig. 1. The shaft is supported rotatably by bearings 13 and driven by a variable speed motor 14 at one end of the shaft 12. A bar 10 is secured to the outer end of an arm 11 at the opposite end of the shaft 12 from that attached to the variable speed motor 14. Guide wheels 9 and 9' for distributing an optical fiber to the guide roller groups are provided on both ends of the bar 10. Guide wheels 9 and 9' align an optical fiber such that it may be wound about the circularly arranged groups of guide rollers 2. A chain sprocket wheel 15 is mounted on the shaft 12 and is coupled mechanically to a chain sprocket wheel 17 mounted on a threaded shaft 18 so that threaded shaft 18 is driven by variable speed motor 14. As shown in Fig. 1, the threaded shaft 18 rotates in the same direction as the shaft 12. The threaded shaft 18 is mounted rotatably through bears ings 21 and 22 and has a right-handed screw 19 and a left-handed screw 20. The screws 19 and 20 are engaged with nuts 23 and 23' which are secured to the bases 8 and 8', respectively. As so arranged, the guide roller groups "bl' and glc! move laterally in opposite directions to each other as the threaded shaft 18 turns. The pitch of the screws 19 and 20 is equal to that of the wire accumulating guide rollers 2. Therefore, when the shaft 12 makes one revolution, the threaded shaft also makes one revolution, and the guide roller groups move horizontally a distance "P" equal to the separation between grooves on each of the guide rollers 2. When a line drawing operation for optical fibers is carried out under normal conditions, the optical fiber is advanced through the guide wheels 26', 9', 9 and 26 in the direction of arrow "a" as shown in Fig. 1. If the optical fiber is broken during a tension test, it is desirable to cease advancement of any fiber emerging from guide wheel 26 while maintain- ing advancement of the fiber toward guide wheel 26'. When a break occurs, the variable speed motor 14 is activated to rotate the shaft 12 to begin taking up advancing fiber from the line drawing unit. As the shaft 12 is turned in the direction of arrow "e" in Fig. 1, the arm 11 and the bar 10 are turned as shown in Fig. 2, and accordingly the fiber is wound about the guide roller groups in the direction of arrow "d" as shown in Fig. 2. The optical fiber strand is thus accumulated on the guide roller groups while being drawn from the line drawing unit at a constant drawing speed. The rate of accumulation is determined such that the fiber advances from guide wheel 26 at a speed which allows a second taking unit to lay the optical fiber. As the shaft 12 turns, the optical fiber is accumulated by winding it around the two guide roller groups "b" and "c". The optical fiber strand is also distributed evenly to the grooves 3 of the guide rollers 2. The threaded shaft 18 is turned in the direction of arrow "f" in Fig. 1 through cooperation of the chain sprocket wheels 15 and 17 and the chain 16. Because the chain sprocket wheels 15 and 17 each have the same number of sprockets, the threaded shaft 18 turns at the same rate as the shaft 12. Since the pitch of the screws 19 and 20 equals that of the guide rollers 2 as described above, the guide roller groups are moved horizontally a distance equal to the separation between the grooves of the guide rollers 2 as the shaft 12 completes one revolution. Therefore, the optical fiber is distributed equally to the guide roller groups by providing one complete winding about each group for each groove. The guide roller groups are designed to have as many grooves 3 as ordinarily required to accommodate the winding of an optical fiber strand drawn out during the time required to restore the broken line. When the line accumulating device has wound the fiber to maximum capacity, the guide roller groups tlb and "c" have been moved to the positions indicated by the dotted lines in Fig. 1. At this point, the guide roller groups have been moved a distance "w" equal to the distance "W" between the first groove and the last groove of each guide roller 2. Once the broken line is restored, the second taking unit draws out the fiber at a higher speed than the line drawing speed of the line drawing unit. The line accumulating device is operated to turn the shaft 12 in a direction opposite to that which it is turned during the line accumulation procedure. As a result, the fiber accumulated on the guide roller groups is unwound for advancement to the second taking units. When all of the accumulated fiber has been unwound, the line winding speed of the second taking unit is made equal to the line drawing speed of the line drawing unit. Thus, normal operation is restored. The line accumulating device as described is disadvantageous in that it must be constructed to accommodate the total amount of movement of the two guide roller groups over the distance equal to twice the width of each roller group, "2W". AddIng the width of each guide roller group to the distance travelled by each group results in a minimum length of the device equal to four times the width of each roller group, "4W". Since the guide rollers groups Ilbll and "c" are secured to the bases 8 and 8?, the weight of each roller group must be supported by the guide bar 24. Therefore, the guide bar should have a length of at least "4W" and be strong enough to support the weight of at least two guide roller groups. Also, because the slide mechanisms supporting the bases 8 and 8' must be located outside the cylindrical range of rotation of the guide bar 10, the device is necessarily large in height as well horizontal span. The invention is constructed to wind the fiber around guide roller groups as described above. However, its structure is considerably more compact than the above-described device. The guide wheels which distribute fiber to the guide roller groups are made to slide laterally relative to the body of the device. This eliminates the sliding movement of the guide roller groups and the structure necessary to accommodate such movement. Referring to Fig. 4, the guide rollers 2 of the guide roller groups "b" and "c" are mounted rotatably between side plates 6 and 7, and 6' and 7' in such a manner that, for each guide roller group, the guide rollers 2 are arranged at equal intervals on a circumference as in the above-described device. The guide rollers 2 are positioned so that grooves 3 are shifted in the axial direction. The side plates 7 and 7' are fixedly secured to a base 27. Guide wheels 26 and 26' for introducing the optical fiber strand to the guide roller groups "b" and "c" are mounted on the side plates 7 and 7', respectively. A shaft 12 extends along the central axis of the guide roller group "c" and is rotatably supported by bearings 13. The shaft 12 is driven by a variable speed motor 14 which is provided at one end of the shaft 12. An arm is secured to the other end of the shaft 12. The outer end of the arm 11 is secured to a guide bar 29. As shown in Fig. 5, guide rollers 9 and 9' for distributing an optical fiber to the guide roller groups "b" and "c" are rotatably mounted on movable blocks 28 and 28', respectively, which move horizontally along the guide bar 29. A threaded shaft 30 is rotatably supported on the arm 11 and through bearings 32 and 32' on supports 31 and 31' which are secured to both ends of the guide bar 29. The threaded shaft 30 is arranged in parallel with the guide bar 29. The threaded shaft 30 has threaded parts 33 and 34 on both sides of the arm 11 which are engaged through nuts incorporated into the blocks 28 and 28', respectively. The threaded parts 33 and 34 are a right-handed screw and a left-handed screw, respectively. The pitch of the screws 33 and 3G is equal to the pitch of the grooves of the guide rollers 2. Therefore, when the threaded shaft 30 makes one revolution, the movable blocks 28 and 28' are displaced as accordingly determined by the pitch of the screws the distance between each thread. This distance is equal to the separation between grooves 3 of guide rollers 2. The movable blocks move in opposite direction to each other. As shown in Figs. 4 and 6, a chain sprocket wheel 35 is mounted on the threaded shaft 30 and is coupled mechanically by a chain 36 to a chain sprocket wheel 37 mounted on the side plate 6' of the guide roller group "b" in such manner as to be coaxial with the shaft 12. Both chain sprocket wheels 35 and 37 have the same number of teeth. Therefore, one complete revolution of shaft 12 will cause the threaded shaft 30 to turn one complete revolution. Under normal line drawing operations, the optical fiber advances through the guide wheel 26', the distributing guide wheels 9 and 9' and the guide wheel 26 in the direction of arrow "a" to the winding unit. When a break occurs, it is desirable to cease advancement of the optical fiber emerging from guide wheel 26 to the winding unit and maintain advancement of the optical fiber from the line drawing unit toward guide wheel 26'. The variable speed motor 14 is activated so that the shaft 12 is turned in direction of the arrow "h." As the shaft 12 is turned in this manner, the arm 11 and distributing guide rollers 9 and 9' are turned about the guide roller groups in the direction of the arrow "g" as shown in Fig. 6. This winds the optical fiber around the guide roller groups. # AceAccordingly, the fiber is accumulated on the guide roller groups while being drawn out of the line drawing unit at a predetermined drawing speed without interruption. Because the chain sprocket wheel 37 is coupled through the chain 36 to the chain sprocket wheel 35 on the threaded shaft 30, the chain sprocket wheel 35 is turned in the direction of the arrow "i" as shown in Fig. 4. This turns the threaded shaft 30 and, the guide wheels 9' and 9 are moved right and left by means of the threaded parts 33 and 34, respectively. As the optical fiber is accumulated on the guide roller groups, it is distributed evenly along the length of the guide rollers 2 by guide wheels 9 and 9? which move the distance "P" between each groove 3 of the guide rollers 2 for each winding of the optical fiber around the guide roller groups. The device is designed to have a number of grooves 3 which provide for sufficient accumulation of fiber given the normal time required to restore the line drawing operation following a break in the fiber. At the point of maximum accumulation, the guide wheels 9 and 9' are positioned at the inner ends of threaded parts 33 and 34 closest to arm 11. Once the broken line is restored, the second taking unit is activated to take up the fiber at a rate higher than the line drawing speed. The variable speed motor 14 is then rotated in the opposite direction to unwind the fiber about the guide roller groups. Once the accumulated fiber is completely unwound, the rate of advancement of the fiber taken up by the second taking unit is reduced to equal the line drawing speed. Thus, the line drawing operation is returned to normal. As is apparent from the description, in the line accumulating device of the invention the guide roller groups are fixed to the body of the device. This eliminates the need to laterally move the heaviest and bulkiest parts of the device. Furthermore, the device of the invention eliminates the long guide bar and the long threaded shaft found in the conventional embodiment which are provided to slide the guide roller groups from side to side. Therefore, the device of the invention is small in width and height and yields a low manufacturing cost. Furthermore, the device of the invention is advantageous in that only a small space is required for installation and the device can be added to an optical fiber drawing operation without considerable modification to provide spacing between devices.

Claims: CLAIMS 1. A line accumulating device which comprises: two line accumulating members which are confronted with each other in such a manner as to be coaxial with each other; a shaft driven by a variable speed motor and extending along a central axis of one of said line accumulating members; distributing guide wheels which are turnable about said line accumulating members and are movable sidewards; and means for moving said distributing guide rollers at a predetermined pitch with respect to rotation of said shaft, whereby a line is wound on or rewound from said line accumulatis members as said shaft turns. 2. A device as claimed ir. Claim 1, wherein each of said line accumulating members comprises a group of guide rollers which are rotatably arranged at equal intervals on a circumferen#:e, each guide roller having grooves arranged at PredfJtermined intervals, and said distributing guide whels are moved as much as the pitch of said groovy whenever said shaft makes one I revolution. 3. A device as claimed in Claim 2, wherein said line is an opyrtcal fiber.

Inventors: MITSUNAGA, YUTAKA, YAMAZAKI, TAKASHI C/O YOKOHAMA WORKS
Applicants: NIPPON TELEGRAPH AND TELEPHONE CORPORATION, SUMITOMO ELECTRIC INDUSTRIES LIMITED
Application year: 1983
Main classification: B65H51
IPC codes: G02B6, B65H51, C03B37