Conveying Ideas For Efficiency, Safety And Profitability
- Published: Tuesday, 01 April 2008 08:00
One of the most important ó yet maintenance-intensive and dangerous ó pieces of production equipment is the conveyor. As this machinery has gotten more efficient over the years, manufacturers of conveyors and components have developed numerous solutions to the inherent problems in conveying aggregate, such as spillage, belt wear and breakage, material contamination, high maintenance requirements, and worker safety and noise exposure. Below is a sampling of available conveyors and conveyor components.
Conveyors subject to hot materials can be damaged over time. The HotSpotIR high-speed scanning system from Ametek is designed to detect hot spots early by sampling 100,000 high-resolution temperature points every second. The system has been developed as an improvement over traditional methods such as visual inspection or single-point pyrometers, which often are unable to detect hot spots on a moving conveyor.
The compact, high-resolution system measures temperatures ranging from 68 to 482∞ F, by sampling 1,000 points with each scan. The scanner then outputs a signal of the highest temperature sensed, updating it with the next scan 1/100th of a second later. Temperature measurements are sent continually to a dedicated processor that can trigger an alarm or signal the conveyor operator to take corrective action. The system features a compact, high-speed line scanner that features a minimized depth and base ìfootprintî for installation in restricted spaces. A durable sapphire window provides reliable protection for the system's optics, and a built-in laser targeting system aids alignment to the target. Alarms can be used to trigger water sprays or suppression systems. Alternatively, the HotSpotIR can be positioned above the conveyor to monitor the material in order to determine hot spots and prevent hot items from being loaded and transported.
Designed for easy installation, the HotSpotIR comes with a quick-release mounting bracket that allows for quick fitting and maintenance. A single, quick-release cable connects the sensor to the alarm processor.
High-temperature VA228 roller bearings from SKF Industrial Div. incorporate a dry graphite lubrication technology that increases reliability and service life at extreme temperatures. When pressed against a hard surface, a thin layer of carbon crystals comes off and reduces friction. The company's dry lubrication technology goes one step further than lubricant additives and incorporates the graphite into the bearing, replacing all other lubricants and providing a maintenance-free roller bearing. The graphite lubricant (in the bearing) is in the shape of a crown, surrounding and separating the balls in the bearing; it can handle temperatures ranging between -150 and 350∞ C, at speeds up to 100 rpm.
The ASGCO Safe Guard Return Idler Guard line that works on CEMA B, C and D series idlers up to 7 inches in diameter has been expanded to include CEMA E & F return rollers. The lightweight component is designed to prevent injuries from pinch points and to catch the return idler if it should fall. The transverse support of the new heavy-duty guard is angled to provide a more robust design that prevents bending. Both the mounting brackets and end plates are made from powder-coated A-36 steel.
Ultra High Molecular Weight (UHMW) slotted cage is designed to prevent material buildup and for easy cleaning. Full access to the roller is possible by removing two stainless-steel pins to drop open the side of the cage. All guards are fully adjustable for a wide range of idler sizes and belt widths up to 96 inches.
Masaba Mining Equipment has introduced a 36 ◊ 150-foot Magnum telescoping conveyor that provides constant positive traction and smooth operation of the stinger. This design eliminates cable maintenance issues associated with winch systems, and eliminates the danger of cable breakage and uncontrolled rollback, improving long-term durability.
The conveyor's hydraulic shift axles are designed to provide quick setup from road travel to operational mode. The unit has a patent-pending seamless hydraulic shift from free-wheel road travel to high-torque stacking. Variable-speed power travel promotes improved pile quality and integrity. Standard four-wheel drive system provides positive traction in the field and a swing-axle design reportedly provides the widest and most stable footprint in the industry.
The conveyor is equipped with simple PLC operation, which eliminates material segregation. Four fully functional programs allow users to choose their stockpiling preference via a large color touch screen. The PLC uses all NEMA-class components to ensure reliability in the field.
Conveyor Components' Model RS stop switch is operated by a cable that a worker can pull to instantly stop a conveyor in an emergency situation. It is equipped with a positive safety lock, preventing accidental restarting after the converoy has been shut down. Resetting of the switch requires the operator to push the switch inward and turn it. The cable extends in both directions from the actuating handle, a simple design that eliminates the need for double-ended connections required in two-ended units that use a separate micro-switch for cable in each direction.
Adjustment of actuation force can be accomplished in the field by changing the position of the cable in holes in the actuating arm. Unit is designed for durability, with an aluminum enclosure and a stainless-steel actuating shaft; powder-coated, cast-iron construction and epoxy coating of either casting are optional. The switch is UL- and Canadian Standards Association-listed and recommended by ANSI.
Super Power Magnetic Pulleys from A & A Magnetics provide maximum protection against tramp iron contamination. These self-cleaning pulleys are widely used as head pulleys on belt conveyors and are designed to be equally effective in the separation of both large and fine metal particles from non-ferrous materials.
The Super Power models are specially suited to handle larger volumes of material flow, faster conveyor speeds and deeper burden depths than the company's standard pulleys. The units are constructed with a stainless-steel shell and removable shafts; vulcanized rubber lagging is optional. They are available in standard diameters of 10, 12, 15, 18, 20, 24, 30 and 36 inches. Larger diameters are available on request. Face and shaft sizes also are available, according to customer requirements.
Thayer Scale has introduced a new Strain Gauge Series of load cells, scales and instrumentation. The company's proprietary LVDT weighing technology is designed for ruggedness and the ability to provide highly intelligible signal levels. It also is designed for long-term survival in physically abusive environments or where highly responsive controller action is critical. Applications include very low density belt weighing, high turndown loss-in-weight feeding, extended runtime loss-in-weight feeding, high multiple micro batching on a per-refill basis and ratio (ìslaveî) feeding under dynamic demand conditions.
Flexco recently unveiled its BR6 fastener and fastening system. The new fastener is designed to provide a faster and easier solution to belt tensions and pulley diameters that could not be handled by the BR10, particularly on troughed belts with 20-degree and 35-degree troughing idlers.
The BR6 fasteners can handle tensions from 330 to 400 per-inch-of-width and conveyor systems with pulleys as small as 14 inches and operating tensions at 75% to 100% of tension ratings. The BR6 requires only six rivets per fastener versus the 10 required by the BR10 and can be purchased in full-width strips of 24, 30, 36 and 42 inches. It also can be used instead of vulcanized applications.
The MBRT tool is designed to facilitate the installation of BR6 fasteners. A light aluminum structure and high-strength clamp bar reportedly save 30 to 50 minutes per splice. The scalloped edge on the tool allows BR6 fasteners to nest securely on the bottom side of the belt without the use of clips or a cam rod.
Flexco also offers its 900 Series belt cutter, which cuts belts up to 1Ω inches thick and 84 inches wide. Features include a blade that is guided at the top to ensure perpendicular cuts, a single-sided clamp that allows the belt to fall free from the cutting edge, an integrated belt-grip surface with gentle serrations for added clamping strength and a cambered bottom beam, which provides uniform clamping force across the entire belt width.
Depressing the Quick Clamp latch releases the top clamp beam. Installment is achieved by aligning the clamp beam in the uprights and allowing it to drop into position. Final clamping pressure is achieved with a few turns of the pivoting arm.
The B&W Stormajor barge-loader conveyor from the Aumund Group has an integral Samson surface feeder with a radial outloading boom ó both mounted to an integrated fully mobile chassis, with pneumatic tires for easy movement as a single and fully autonomous machine. The cantilevered outloading boom offers sufficient outreach to move material significant distances.
Material may be received from a local stockpile using a loading shovel to feed the Stormajor. Or, a small truck ramp enables vehicles or dump trucks to discharge directly to the integral Samson feeder, eliminating double handling.
The Stormajor also can be applied to railcar loading. The problem of railcar overloading is addressed with a scale to ensure that only the desired net weight is loaded to each railcar. In this application, a load cell-type weigh idler is included in the outloading boom conveyor and supplied with an inclinometer to measure the boom angle plus a rotary encoder to measure the belt speed.
The new Model SS-3 Pull Cord Switch from Bulk Pro Systems LLC shuts down a conveyor system in an emergency or when maintenance is needed. The switches are connected by a safety cable that runs between the switch arms. When force is applied to the cable, the actuator arm rotates and locks the switch in the alarm position. This activates two micro switches and the manual lockout. Switches are mounted on the walkway side or anywhere the moving parts of a conveyor are accessible.
The switch has a NEMA-4 die-cast aluminum enclosure with a corrosion-resistant urethane enamel finish. The safety-red actuator arm allows for visual indication of status of the switch. The large cover reportedly allows for easy access to wiring and internal mechanics of the switch.
Superior Industries has developed the Moxie idler roll for durability and reduced operating costs. Designed with a high-density polyethylene (HDPE) material, the idler rolls are designed to solve problems caused by abrasive material and buildup.
The idler rolls are manufactured with a SpinGuard seal system that keeps contaminants away from the bearing. The combination of HDPE and SpinGuard seal system minimizes roll resistance and the need for additional horsepower. The units reportedly are quieter than steel and can be retrofit into any manufacturer's idler frame or bracket. They are available in CEMA C or D sizes and fit belt widths of 18 to 72 inches.
Superior Industries also offers the Navigator training idler for correction of misaligned belts. Its unique pivoting mechanism uses uneven pressure, which occurs when a belt mistracks, to pivot the mechanism and guide the belt back into place. Also, the bearings are located in the center, which keeps them free of contaminants and makes them simple to change with no need to replace the entire idler. Rubber lagging sheds material and increases traction to align belts. Navigator training idlers also are available in standard steel; both options are 73/4 inches in diameter and available in belt widths of 30 to 72 inches.
The company also has introduced the Chevron Wing Pulley, a V-shaped pulley that quickly deflects rocks and other fugitive material away from the belt to prevent wing tipping and extend belt life. A round bar-wing cap design provides added belt support and reduces vibration and noise by 50 decibels. The patent-pending pulley is available in diameters of 12 to 42 inches and fits belt widths of 24 to 72 inches.
New HM150 formed rollers from Sandvik offer an alternative to heavier rollers for heavy material. The HM150 design provides customers with high-speed belts all the way up to 36 feet per second. The roller is naturally balanced to minimize vibration, noise and energy consumption ó because the flow-formed tube and hollow shaft are much lighter than a traditional roller. Unit can be used as a garland roller or installed onto a roller frame.
The Pit Viper sand and gravel belt cleaner from Martin Engineering removes sticky sand and wet fines on belts from dredges, sand screws and other sand-processing operations. Its one-piece blade reportedly contains about 20% more urethane than comparable pre-cleaners, which extends service life. The unit uses an aggressive angle of attack to the belt to increase cleaning efficiency. A simple design allows ìone-pin, no-toolî blade replacement. The process of replacement involves dropping the sturdy blade into place on the reinforced steel mainframe and securing it with a wire lock pin.
The product fits head pulleys up to 16 inches in diameter and belt widths from 12 to 42 inches. Belt coverage can be 2 or 6 inches less than belt width to match the width of the cargo on the belt. The item is available as an economical assembly including mainframe, urethane blade and tensioner.
Cross-belt separators manufactured by Bunting Magnetics Co. provide continuous removal of ferrous contaminants from rock, stone and aggregate on open conveyors. High-density, permanent ceramic plate magnet reportedly reaches deep into the product flow and captures elusive scrap, even from fast moving belts. Several models are available for customizing the strength and reach-out of the magnetic field.
A cross-belt design creates a large coverage area whether the unit is suspended parallel to, diagonally, or at right angles to, the conveyor. Tramp iron falls from the unit's cleated belt as it moves the captured metal debris beyond the magnet's face and out of the magnetic field.
Tectron Engineering has unveiled new SST digital controls for use with its T2000, 5000, 8000 and 8600 metal detectors. The controls include a two-line LCD display and a membrane keypad for adjusting sensitivity and clip time. In addition to a user-friendly design, the new controls are designed for greater resistance to false trips, particularly from FM and CB radios. They allow a self-test circuit that constantly monitors the unit's electronics and antennas for problems. If a problem is detected, a fault light/output is activated to tell the operator the metal detector is not functioning properly.
An optional RS232/485 connection includes a logbook for recording the date and time of metal detections, changes to the settings or power on/off; the logbook can be output to a PC for data analysis and archiving. SST digital controls can be retrofit to an existing metal detector in minutes.
A Permanent or Electro Stationary Suspension Magnet from Global Equipment Marketing's Magnetics Div. can eliminate the hazard of getting a loader or bucket tooth caught in the crusher. The cost for a magnet to prevent this problem is less than the cost of the repairs, not to mention downtime and failure to be able to operate during repairs. Moisture- and dust-proof, the permanent magnets have no moving parts to wear or break. They are constructed of advanced magnetic materials in a computer-designed magnet circuit for strength. All magnets are enclosed in heavy-duty stainless-steel or manganese impact plates and all welded construction.
Each unit comes with a lifetime limited warranty against loss of magnetic strength. All magnets are equipped with eyebolts or pads for suspension as well as a set of adjustable suspension chains with turnbuckles and a slide tray or belt stripper for safe, easy cleaning of the magnet face. Units are available for all conveyor widths to 84 inches and material burden depths from 1 to 16 inches.
For deeper burden depths, faster than normal belt speeds or requirements for removal of heavier than normal tramp iron, an Electro Stationary Suspension Magnet is available for conveyor widths to 84 inches and burden depths from 1 to 28 inches. These units have no external expansion oil tank, which can create condensation and potential for damage. The magnet coils and transformer oil are enclosed in stainless-steel impact plates. Coils have a 10-year warranty. All electro magnets are equipped with NEMA 4 junction boxes, eyepads for suspension and adjustable suspension chains with turnbuckles. A matching NEMA 12 rectifier is available for converting the AC input power supply to the required magnets' DC output.