Mike McNulty 2017-11-07 02:45:34
by Mike McNulty, Editor Wire & Cable Technology International Individual wires, conductors and cables are twisted together in a helical pattern, in continuous or alternating directions, around the central axis of the finished product by stranders, bunchers and cablers. The terms— stranders, bunchers and cablers—are loosely used in a variety of ways depending on the factory, industry sector or region. Some people call all rotating machines stranders, for example, and many people use the word buncher and strander interchangeably. My personal definitions are contained in two subhead sections of this article: Stranders and Bunchers and Cablers. Stranders Traditional stranders are rotating machines in which the reels holding the material to be twisted are located within the rotating element of the machine, and the take-up reel of the strander is located outside of the rotating element. Examples of traditional strander types are rigid, planetary, tubular (tube) and bow. One other type, the SZ strander, does not fit into my definition, but it will be presented at the end of this section. In stranders, the rotating element makes one full revolution or twist for each complete helical turn (lay) of the stranded product—stranders are single-twist machines. Rigid stranders consist of one or more bays that hold groups of supply reels in a fixed position, and the payoff material is twisted axially as it is stranded into the final product. Each payoff reel axis follows the path of bay rotation. Due to the large amount of rotating mass, rigid strander speed is quite low. These machines are used for making large-diameter cables and products that require layers stranded in opposite directions as each bay can be rotated in a different direction from the others. Planetary stranders are similar to rigid machines with the main difference being that the payoff material is not twisted because the payoff reels are carried in a cradle that is suspended by pintles. This arrangement allows the reel to remain in the same position relative to the machine base during the rotation of the bay—the reel axis remains perpendicular to the floor. Applications for this strander are those in which you do not want to twist the material being stranded. As with rigid machines, the rotational speed is low. In tubular or tube stranders, payoff reels are not rotated around the axis of the finished product. The reels are placed in-line inside of a tube, which is the rotating element. The payoff material comes off of the reel and is directed to the inside or the outside of the tube for stranding. Rotational speeds are much higher than with rigid or planetary machines, and the reels can be configured so that each reel axis is either perpendicular or parallel to the central axis of stranding. In the parallel arrangement, the stranding axis and each reel axis are the same. A bow strander is essentially the same as a tube strander with the difference being that the rotating tube is replaced by a rotating bow for each payoff reel. As the bow weighs much less than a tube, top rotation speeds are higher. Tube and bow stranders are commonly used for seven and 19-wire constructions. Development efforts and design differences on the above-mentioned stranders are focused on tension control, speed control and reducing the downtime associated with loading and unloading the payoff reels. Many excellent solutions are offered by strander suppliers. SZ stranders rotate the payoff material in alternating directions (left-right, clockwise-counterclockwise, S-Z, etc.), and binders are used to hold the stranded product together. The objective is to eliminate the task of rotating large payoff reels, tubes or bows as the materials are stranded after they come off the reel. Use of SZ stranders is common in the area of fiber optic cable stranding. Bunchers and Cablers Bunchers and cablers are rotating machines in which the supply wires are located outside of the rotating element, and the take-up spool is located inside of the rotating part of the machine. The difference between a buncher and a cabler is in the material to be processed: bunchers process uninsulated wire/conductors while the cabler processes insulated cables. Twinners, machines to make twisted pairs of cables, can be classified as a type of cabler. The rotating element in bunchers and cablers is the bow, and the two main types are the single-twist and the double-twist buncher or cabler. In a single-twist machine, the finished product is twisted once for every complete bow revolution, and a double-twist unit twists the wires or cables twice for every bow rotation—one twist at the entrance of the bow and the other at the bow exit. The result is a doubling of the linear production speed with the same level of bow rotation. When bunchers were first developed, they were designed exclusively to make lower-quality, nongeometric constructions of wires, but as buncher technology improved, the buncher was able to make many higherquality, geometric products—seven, 19 and 37-wire constructions—as well as high-performance communication cables at quality levels equal to products made on single-twist bunchers, cablers and stranders. Investment costs for bunchers and cablers are usually lower than for equivalent stranders. There are dozens of knowledgeable suppliers of stranders, bunchers and cablers for all wire and cable applications. Contact them to learn more on rotating processes. Developments From a development standpoint, rotating machines see a good amount of innovation each year. Trends and developments that have appeared in this magazine over the last few years include the following: • Double-twist machines that incorporate stretch forming and straightening technology to ensure that the crowning effect is eliminated and the produced bunched strand is straight. • Specialized large planetary stranders for assembling high-strength and complex umbilical cables for subsea installation. • Roll forming of compact aluminum conductors using single input wire (SIW) technology. • Improved SZ stranding for fiber optic cables • Single-twist cablers designed to compete with conventional drum twisters, processing the same product mix at higher speeds. • Multiple-bay planetary cabler with two sections that can be coordinated to operate both right-to-left and left-to-right direction independently as well as being electronically ‘locked’ to rotate at the same rpm in the same direction. • Innovative flyer bow designs and single-bow rotating machines. • Reduced energy consumption. • “Four twist” and “triple twist” technology. • Wireless tension monitoring and slip-ring systems that use fiber optic communication. • Spool run-out detectors for stranders and cablers. • Improved guidance systems and tension control. • Increase in electronic and digital control of rotating machinery. • High-powered PC controls and sophisticated, easyto- use touch-screen operator interfaces. • Larger-capacity rotating machines. • Automated loading and unloading systems. • Integrated quality and process control devices for monitoring, controlling and reporting finished product data and production levels. • Improved traverse systems on the take-up reels. • Reduced floor space. • Reduced noise emissions and improved safety. References: “Introduction to Bunching and Stranding,” David C. Hallam, Oxford Instruments, Nonferrous Wire Handbook, Volume 3, WAI, 1995. “Spotlight on Rotating Machines”, Wire & Cable Technology International, 1997-2015. BARTELL® 6321 Elmer Hill Road Rome, NY 13440 USA Tel: +1 315 336 7600 Fax: +1 315 336 0947 Internet: www.bartellmachinery.com HONTA Inc. 29 County Line Rd. Branchburg, NJ 08876 USA Tel: +1 908 370 3117 Email: info@HontaInc.com Internet: www.jshonta.com Howar Equipment Inc. 499 Edgeley Blvd. Unit 12 Concord, Ontario, Canada Tel: +1 905 669 4010 E-Mail: email@example.com Internet: www.HowarEquipment.com KALMARK Integrated Systems Ltd. 214 Victoria Street Simcoe, Ontario, Canada N3Y 4K2 Tel: +1 519 428 2262 Fax: +1 519 428 1358 Internet: www.kalmarkltd.com Kinrei of America Donnelly Reels Division 557 Route 23 South, Suite 3 Wayne, NJ 07470 USA Contact: Sean Donnelly Tel: +1 973 677 9500 Email: firstname.lastname@example.org Internet: www.kinreiusa.com Frigeco USA, Inc. 67 Beaver Avenue, Corbit Building, Suite 12 Annandale, NJ 08801 USA Tel: +1 908 894 5801 • Fax: +1 908 894 5809 Internet: www.mflgroup.com M.F.L. U.S.A. Service Corp. 70 Industrial Drive Cumberland, RI 02864-6021 USA Tel: +1 401 334 1151 Fax: +1 401 334 1161 Pioneer Machinery USA 55 Madison Avenue, Suite 400 Morristown, NJ 07960 USA Tel: +1 973 285 3211 Fax: +1 866 892 Service: +1 201 532 3025 Email: email@example.com Internet: www.pioneermachinery.us Roteq Machinery Inc. 317 Bradwick Dr. Concord, Ontario, Canada L4K 1K5 Tel: +1 905 660 8800 Fax: +1 905 660 8898 Email: firstname.lastname@example.org Internet: www.roteqmachnery.com SAMP USA, Inc. 10522 Governor Lane Blvd., Williamsport, MD 21795 USA Tel: +1 301 223 8584 • Fax: +1 301 223 8542 Email: email@example.com Internet: www.sampinc.com SAMP Division SAMPSISTEMI Via Saliceto No. 15 40010 Bentivoglio (Bologna) - Italy Tel: +39 051 6319 411 • Fax: +39 051 37 08 60 Email: firstname.lastname@example.org Internet: www.sampsistemi.com
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