Flexco® 8-Rivet, Special-Alloy Conveyor Belt Fasteners Target Higher-Tension Trends in Underground Mining
11 March 2002
Flexco® RAR8, the latest addition to the Flexco® SR™ Scalloped-Edge™ rivet-hinged conveyor belt fastener system, features a high-strength 8-rivet attachment for reliable splicing on longer, wider, more heavily loaded panel and mainline belts in underground mining. Designed for longer life on higher-tension belts with mechanical fastener ratings up to 1500 PIW (263 kN/m), RAR8 fasteners also offer the advantages of RustAlloy®, a low-chrome stainless steel alloy from Flexco that resists corrosion and wear resulting from acidic mine water, abrasive fines and chemical attack.
Developed as a step up from RAR6 five-rivet fasteners recommended for 1000 and 1200 PIW longwall conveyor applications, RAR8 fasteners will fit the same belt thickness range, from 13/32" to 11/16" (10.5mm to l7mm), and will wrap smoothly around the same minimum end-pulley diameter of 18" (145mm) under full-rated tension.
The SR fastener design grips the belt end between top and bottom plates, approximately 1½ " (38mm) wide and joined at one end by two wide hinge loops. Each fastener segment is secured to the belt end with a hammer-driven, self-setting rivet attachment technique pioneered by Flexco to simplify installation and shorten downtime.
The patented Scalloped Edge design, recently introduced as an improvement to Flexco SR fasteners, results in a lower profile splice that passes more smoothly under belt cleaners and skirtboards. Visibly different from other fasteners, the Scalloped Edge design features leading/trailing edges formed into a concave, scalloped shape with more-prominent edge coining (bevelling). These features allow the fastener plate ends to embed deeper into the belt cover with less effort, reducing splice height even on belts with top covers too thin to allow skiving (countersinking).
Other features of Scalloped Edge design help assure proper installation. Fasteners are supplied in continuous strips that provide uniform spacing and alignment across the belt. Each fastener top plate contains a viewport, which allows the installer to see that the belt end is properly butted against a belt stop formed into the fastener's bottom plate. By allowing visual confirmation, the viewport promotes accurate, uniform positioning across the squared belt end, which produces a straighter splice that results in longer splice life and a truer-tracking belt.
Fastener strips for RAR8 are offered in five lengths to suit standard belt widths of 48", 54", 60", 72" and 84" (1200mm, 1350mm, 1500mm, 1800mm and 2130mm). Strips are formed with break-away bridges between fasteners, which allow any number of fasteners to be broken off by hand to fit non-standard belt widths.
While the RAR8 can use any hinge pin currently offered for R6 fasteners, the pin recommended for RAR8 is Flexco's® ACS6 3/8" (10mm)-diameter Bare Armored 300 Series cable.
The RAR8 fastener is installed with one of five different rivet lengths, determined by belt thickness. Manufactured of Type 409 Stainless Steel, the rivets are pre-assembled with special break-away pilot nails that penetrate the belt without damaging or weakening the belt carcass. This method speeds and simplifies the installation process and reduces downtime by avoiding the time-consuming hole-punching and nut/bolt assembly required with some plate-type fasteners.
The high-strength SR rivet attachment technique pioneered by Flexco needs only portable installation tools and a hammer. Tools include the Flexco® MSRT8 multiple-rivet driving system, which uses pre-loaded guide blocks to hold 20 rivets in alignment over five rivet holes of four adjacent RAR8 fastener plates. A special five-pronged drive rod, inserted into the top of the loaded guide block, enables five rivets to be hammer-driven and set simultaneously, leaving only the three additional rivets to be driven individually. The number of blocks needed to fully cover belt width can be kept pre-loaded with rivets in their metal carrying case for immediate use.
