Rexnord's new Falk V-Class line of gearboxes.
Conveyor Technology on Track for Higher Performance
New products emphasize increased power, strength, reliability—and simplicity
By Russell A. Carter, Managing Editor
A well-running mine conveyor normally doesn't attract a lot of attention—but that can change within a few seconds.
An unplanned conveyor stoppage, for whatever reason, is a matter usually dealt with immediately and the attention level rises exponentially. If the conveyor is part of a mine's production chain, extended stoppages translate quickly into reduced revenue flow, possibly aggravated by the additional costs of unscheduled maintenance or repairs.
The fact that conveyors, at first glance, look mechanically simple and operate quietly and effectively masks a vast range of component choices and performance variables that often must be considered in the design phase, spanning a range that includes everything from load-material characteristics, capacity requirements and external environmental conditions to belt size and type, pulley and idler specifications and power requirements. If the system's route is long or uphill, downhill or twisting and turning, another layer of design problems is added to the stack.
So it's not surprising conveyor systems and component suppliers stress power, reliability, safety and simplicity in new-product announcements. The failure of one critical component can literally stop a belt—and the mine—in its tracks, and complex mechanisms generally aren't amenable to quick and simple repair solutions. These are the factors driving conveyor builders and vendors to keep steadily improving the scope and depth of their product lineups. In this article, we pull together recent developments that reflect advances or improvements in conveyor technology.
Siemens' Drive Technologies Division believes its gearbox customers prefer not to be dependent on customized products for application-specific drive tasks; they want to be able to use standard gearbox models. This means that standard gearboxes must be designed with built-in flexibility that allows them to easily be adapted to specific applications. Siemens said it is now meeting these requirements by offering a range of gearboxes that will be known as the Flender SIG (Standard Industry Gearbox) line. The first type series covers two-stage to four-stage helical gearboxes and bevel helical gearboxes for a torque range that will eventually reach up to 125,000 Nm.
According to the company, torque ratings in the new line will be up to 15% higher when compared with previous models, without a need for increasing unit dimensions. The new gearboxes also will be lighter than their predecessors and a refined sizing approach will allow customers to select the right gearbox solution for their installation requirements. Standardized connections offer flexibility in terms of mounting options, such as those for temperature control or gearbox lubrication.
The first phase of the product launch focuses on two- to four-stage helical gearboxes and bevel helical gearboxes covering a torque range of 3,600 to 125,000 Nm. During subsequent stages, the range will be expanded to offer a total of 20 sizes with torque ratings up to 500,000 Nm. Units with torque ratings beyond that will be available from the existing modular range.
Drives: Torqueing UpRexnord pointed out one of the most distinguishable features of the new drive line is a horizontally split housing. Its shape and features were designed through the use of Computational Fluid Dynamics (CFD) to enhance the drive's thermal dissipation qualities. Cooling fins on the housing help to reduce oil temperature, and proprietary oil feed passages in the housing improve lubrication and provide additional cooling capability. An oil sampling port is built into the housing to allow quick checking of oil condition.
New design elements improve the
line's torque capacity, including:
• 25° pressure-angle gear teeth;
• Case-hardened, ground gears;
• Optimized bevel and helical tooth
forms that ensure full contact under
load;
• Proprietary peened gear teeth;
• Gear sets up to AGMA Class 12; and
• A heavy-duty ductile iron housing that
withstands shock loads.
Features that improve installation, serviceability and replacement characteristics include removable, adjustable feet that allow drop-in replacement for current product lines, and can adapt for replacement of competitor drives and different shaft centerline heights. Base- mounted units can be repaired in place, and the split housing allows easy disassembly/assembly for maintenance of bearings and gearing.
The drive incorporates no-leak seals with oil drainbacks and purgeable grease chamber to eliminate leaks. An optional, DuraPlate cooling system requires no water or electricity to operate and achieves optimal cooling to fully utilize the unit's unparalleled torque density.
The Falk V-Class drive line offers a torque range extending up to 3 million in-lb (341,000 Nm), horsepower ratings of 15 to 10,000 hp (11 to 7,500 kW) and both parallel and right-angle shaft configurations.
The belt, according to Veyance, is capable of conveying 10,000 tons per hour of ore the height of the Empire State Building in a single flight, or conveying material overland 25 miles in a single flight, explained Terry Graber, Veyance's technical manager for conveyor belts.
"The heart of the Flexsteel ST10,000 is the splice," said Graber. "With a belt of this magnitude, it's all about making sure the steel-cord splices will hold up in service. We're the only belt manufacturer with development capabilities to test splices in- house at these high tensions."
Flexsteel ST10,000 uses an innovative splice design Veyance says has been confirmed at over 50% dynamic splice efficiency. Graber explained Veyance's two-pulley dynamic splice testing machine enabled the company to advance splicing technology for high- tension Flexsteel belts to meet the standard set by DIN 22110, Part 3.
"The splice strength we've proven in our Marysville, Ohio, Conveyor Belt Technical Center shows the ST10,000 is the highest tensile strength belt in the world," said Graber. "In addition, it allows for the highest lift or drop and the longest continuous flight without transfer points. Simply put: it's stronger than any other belt out there."
The longer flight capability of the ST10,000 allows mining operations to span longer distances without transfer points. Improving operations by eliminating dust, noise and chute blocking are additional factors that lead to lower capital costs for mines.
"With the ST10,000 you could redesign the 8-mile, 5,000-foot descent of the Los Pelambres conveyor system north of Santiago, Chile, with two flights instead of three," said Graber.
Meanwhile, Germany-based belting supplier ContiTech AG announced two advances in its product lineup. It developed and is testing a rubber compound it claims reduces a belt's rolling resistance by up to 20%; and it improved the "troughability" of its ContiClean AH anti-stick conveyor belting—also the result of its advancse in rubber compound formulation.
According to the company, ContiClean AH belting was designed to provide a surface that can efficiently handle ultra-sticky material like desulphurized gypsum, unfired clay, titanium dioxide or wet ash. The new belting now can be troughed to a greater extent, thus increasing its conveying capacity. The new rubber compound also allows the belting to operate efficiently in temperatures as low as –25°C.
The new line offers standardized panels that allow a systematic approach to guarding, with flexibility to fit virtually any conveyor design. Wedge clamps allow guarding panels to be removed and reinstalled quickly so systems can be expanded or relocated as needed. A variety of wedge bolts and bracket sizes are available to suit a wide range of mounting options.
The guards are self-supporting and feature a modular design that installs on supplied angle-iron structure, eliminating the need to attach directly to conveyor equipment. Integrated handles reduce the number of parts and tools required. Guards are available in a range of sizes up to 36 x 50-in. (91 x 127-cm) panels, and can be used in combinations to accommodate various conveyor systems. They can be specified in powder coated orange or painted safety yellow, and can be purchased with or without mounting hardware.
Thermo Fisher Scientific now offers addressable modules that can connect to conveyor protection switches to safeguard equipment and protect personnel. The modules are incorporated into safety cable pull switches and belt misalignment switches, traditionally mounted along the sides of conveyors. If a switch enters an alarm position, the addressable module sends a signal back to a programmable logic controller (PLC) indicating where an incident has occurred.
The conveyor protection switches, equipped with addressable modules, are wired to a master module that can handle up to 128 different identification (ID) addresses. The master module control is capable of sending ID address information to the PLC using Modbus-RTU, Allen Bradley, Siemens and Schneider protocols, allowing users to easily identify where the incident occurred. Using a quick-connect handheld device, the switch operator is also able to program each switch with an ID number of choice.
"Cord Guard XD uses patent-pending inserts to detect belt rips caused by an object that becomes stuck in the conveyor structure." said Bret Hall, general manager conveyor belt and conveyor belt services for Veyance Technologies. Patented RFID technology is used to uniquely identify each of the rip inserts in the event that they are damaged, permitting Cord Guard XD to correlate its rip insert map with the physical conveyor belt to reduce nuisance alarms. "Cord Guard XD's control unit can be accessed via Ethernet connection to a computer or a plant's operations network. The output includes a display showing the full width and length of the conveyor belt," said Hall.
The location and identification of each rip insert is prominently displayed. When an insert is damaged, the image changes to reflect the location and extent of a rip. The same output also shows the location and severity of any damage to the reinforcing cords inside steel cable belts.
The key monitoring components of Cord Guard XD are the patent-pending continuous arrays, which are designed to identify any rip events occurring across the full width of the belt. These arrays are permanently installed in both the loading and discharge areas of the conveyor system, where rip damage is most likely to start. In the loading area, a profiled array is used to detect rips where the conveyor belt is troughed. A flat array is used on the return side of the belt right after the head pulley to monitor for rips starting in the discharge area.
The Cord Guard XD control unit can be accessed via an Ethernet connection to a computer or to a plant's operations network. The Web-based platform displays the location and identification number of each rip insert. By clicking on the image of any rip insert, additional details on its condition will be displayed at the bottom of the screen. When an insert is damaged, the image changes to reflect the location across the width of the belt and the extent of the rip. Then the Cord Guard XD control unit immediately sends a signal, which can be programmed to stop the belt operation.