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News Release from: Flexco (Flexible Steel Lacing Company) | Subject: SR fasteners
Edited by the Engineeringtalk Editorial
Team on 18 March 2003
Fasteners get to grips with bigger belts
Three larger sizes of Flexco scalloped-edge SR rivet-hinged conveyor-belt fasteners extend this patented design improvement to heavier duty, thicker-belt applications.
Three larger sizes of Flexco scalloped-edge SR rivet-hinged conveyor-belt fasteners extend this patented design improvement to heavier duty, thicker-belt applications The scalloped-edge design, now offered in larger R5.5 and two R6 sizes in addition to the original and smaller R5 size, provides a lower-profile belt splice that results in easier installation, smoother passage under belt cleaners and longer splice life
This article was originally published on Engineeringtalk on 13 May 2002 at 8.00am (UK)
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Noticeably different from familiar earlier Flexco SR fasteners and imitations, the scalloped-edge design features leading/trailing edges formed into a concave, scalloped shape with more-prominent coining (bevelling).
These features allow the fastener plate ends to embed deeper into the belt cover with less effort, for reduced splice height in installations that do not use skiving (countersinking).
With deeper installation, plus the scallop and coining to reduce the initial leading-edge contact area, this design invites belt scraper blades to ramp up and over the plates easily, without encountering any hard edge impact.
Installed with the same tooling previously used for Flexco's standard SR rivet hinged fasteners, the scalloped-edge design makes proper installation simpler.
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All fastener sizes in the SR Series are supplied in strips to assure uniform spacing and alignment across the belt, and the scalloped-edge version adds a viewport in the top plate of every third fastener segment.
This allows the installer to see that the belt end is properly butted against an internal belt stop formed into the fastener's bottom plate.
Accurate, uniform fastener positioning across a squared belt end assures straighter splices that promote longer splice life and truer-tracking belts.
Scalloped-edge fastener strips are offered in a variety of lengths to minimize waste by approximating standard belt widths up to 1800mm.
Extra-length strips ranging from 900 to 2130mm are offered with a special variation of the largest SR size, designated RAR6LP, which combines RustAlloy with a 24% lower profile for maximum compatibility with tight-fitted cleaner blades.
In all sizes, strips are formed with individual fastener segments joined by breakaway bridges, which allow segments to be broken off by hand to trim the strip to any specific belt width.
These easily separable connections also let new splices conform automatically to troughing idlers on first pass.
Across the extended range of scalloped-edge sizes, one size or another will accommodate belts ranging from 6 to l8mm thick with mechanical fastener ratings up to 140kN/m, and will operate smoothly around pulley diameters as small as 230mm.
Each scalloped-edge SR fastener segment consists of top and bottom plates joined at one end by two hinge loops.
Each top-and-bottom plate segment sandwiches the belt end and is secured with a high-strength, five-rivet attachment technique pioneered by Flexco.
Plate segments are installed side-by-side across both belt ends, the loops from both belt ends are meshed, and a hinge pin is inserted to lock the joint together.
The rivets are pre-assembled with special break-away pilot nails that penetrate the belt without damaging or weakening the belt carcass.
Because the rivets are self-setting, they install easily from the top of the belt.
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.
In contrast to belt splicing systems that require complicated machinery for installation, Flexco rivet-attached fasteners are installed on-site with an easy-to-use, portable installation tool and a hammer.
The installation tool holds the belt end and fastener strip in precise alignment while the rivets are driven in.
The same hammer blows that set the rivets also compress the fastener plates into the belt cover.
This simultaneous action automatically maintains each increase in compression, giving the splice a tight, full-width grip that helps prevent belt tension from pulling only on the rivets.
An optional multiple-rivet driving system (MSRT) further reduces installation time with preloaded guide blocks that each hold 20 rivets in alignment over the rivet holes of four adjacent scalloped-edge fastener plates.
A special five-pronged drive rod, inserted into the top of a loaded guide block, enables five rivets to be hammer-driven and set simultaneously.
The number of blocks needed to fully cover belt width can be kept preloaded with rivets in their metal carrying case for immediate use.
For even faster block reloading, rivets are available in Flexco rapid loader assemblies that hold five rivets in the SR pattern for simultaneous insertion.
Standard material for all scalloped-edge sizes is pregalvanised high-strength steel.
The original R5 size remains optionally available in Type 316 stainless for extra resistance to abrasion, acids, corrosive chemicals and magnetic attraction.
Larger sizes, optionally available in RustAlloy, are not offered in Type 316 stainless.
RustAlloy is the standard and only material offered for RAR6LP.
Rivets for all sizes are offered in both standard and stainless steel.
A variety of Flexco's standard 6mm-diameter SR hinge pins suits different operating conditions, offering steel cable, stainless steel cable and armoured cable, all in either bare or self-lubricating nylon-sheathed construction.
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