Alloy rollers

Roller pumps are among the least expensive and most widely nsed of all sprayer pumps. They provide moderate volumes (8 to 30 gpm) at low to moderate pressure (10 to 300 psi). Often used on low-pressure sprayers, roller pumps are positive-displacement, self-priming pnmps. The rollers, made of nylon, teflon, or rubber, wear rapidly in wettable powders but are replaceable. A pump that will be subjected to such wear should have a capacity at least 50 percent greater than that needed to supply the nozzles and agitator. This reserve capacity will extend the life of the pump. The pump case is usually cast iron or a nickel alloy. Roller pumps are best for emulsifiable concentrates, soluble powders, and other nonabrasive pesticide formulations (Figure 14B). 

The rotary drill bits are generally made from quench and tempered steel alloys such as AISI 3115 to 3120, 4620, 4815 to 4820 and 8620 to 8720. The only corrosion related problem that can arise may result from a hydrogen sulfide environment. The bearing in the roller rock bits can be damaged by H S contamination of drilling fluid. However, a well conditioned drilling fluid at... 

Silent chains are similar to roller chains in that each has a master or connecting link to facilitate ease of installation and removal from a machine. They are usually made of high-carbon steel or heat-treated steel alloys. As a result, this type of chain provides trouble-free service for extended periods. 

All AB, alloys are very brittle and are pulverized to fine particles in the hydrid-ing-dehydriding process (see Sec. 7.2.1). Thus electrodes must be designed to accommodate fine powders as the active material. There are several methods of electrode fabrication Sakai et al [35] pulverize the alloy by subjecting it to several hydrogen absorption-desorption cycles, before coating the resulting particles with Ni by chemical plating. The powder is mixed with a Teflon dispersion to obtain a paste which is finally roller-pressed to a sheet and then hot-pressed to an expanded nickel mesh. The fabrication of a simple paste electrode suitable for laboratory studies is reported by Petrov et al. [37],... 

Rolled lead-calcium-tin alloy strip, 14 115 Rolled lead-copper alloys, 14 116 Rolled zinc alloys, 26 594-598 Roller-hearth furnace, 12 289, 290 Roller mills, 18 65 Roller printing, 9 221 Rollin film, 17 354, 373 Rolling-assisted, biaxially textured substrate (RABiTS) technique,... 

The roller atomization process has been applied to the atomization of many metals and alloys, such as lead, tin, aluminum, copper and steel. The production rate is potentially high, and the energy requirement is much lower than in commercial gas and water... 

Another specialty area is coil coating, which involves coating metal coils by continuous operation. Modern roller systems afford speeds of up to 200 m/min. Most coils are made of cold-rolled and surface treated steel, aluminum, or alloys of the latter with manganese or magnesium. Coating systems are based on alkyd or acrylic resins, oil-free polyester, silicone-modified polyester or acrylic resin, poly(vinylidene fluoride), or poly(vinyl fluoride). Water-reducible systems, mainly based on acrylic resins, have been developed for aluminum as well as for steel coils [21-24], Drying is carried out by continuous operation in gas- or oil-heated multichamber ovens. 

The shell of a rotary dryer is usually constructed by welding rolled plate, thick enough for the transmission of the torque required to cause rotation, and to support its own weight and the weight of material in the dryer. The shell is usually supported on large tyres which run on wide rollers, as shown in Figure 16.10, and although mild steel is the usual material of construction, alloy steels are used, and if necessary the shell may be coated with a plastics material to avoid contamination of the product. 

At temperatures above 1150°C, alloys used for the hearth or material handling systems in low and medium temperature furnaces lose strength rapidly (2) and temperatures are reached where ceramic refractories are required to support the work This results in less use of roller-hearth and belt-type hearths and greater use of pushers or walking-beam designs for continuous furnaces. 

Conveyors may be of parallel-chain, mat, slat, woven wire-mesh belt, or cast-alloy type. Automatic tensioning devices are nsed to maintain belt tension during heating and cooling. The prodnct may rest directly on the conveyor or on special snpports built into it. Roller-conveyors are nsed for large pieces. Flame curtains are provided for sealing the ends and for protection of special treating atmospheres. 

Ejection Rail. After compression the lower punch impacts the ejection rail (or on some machines an ejection roller). Upon impact the tablet is broken free from the die side wall and begins to move up the die as the machine rotates. The ejection rail should be made of a tough, abrasion resistant material such as aluminum bronze alloy. 

High strength, high alloy, and often hard steels as well as centrifugally cast or overlay welded rings or rollers require nonconventional methods of machining if pockets or other surface profiliations are to be applied. 

Continuous ribbons can be obtained at speeds of the order of 1 Km/minute. Molten alloys can be injected into the space between spring loaded and cooled rollers spinning in opposite directions. Removal of heat in such a set-up is even better than when a single roller is employed because of the effective use of both the surfaces of the ribbon. Methods have also been developed where drops (instead of jets) of the liquid are... 

The presence of carbide and nitride precipitates in alloy steels can have a beneficial effect on the mechanical properties of the steels concerned. How-ever, the amounts, morphology and distribution of the precipitated phases must be carefully controlled in order to achieve the properties required. Because the presence of hard precipitates in a steel during hot-rolling operations can result in damage both to the rollers and to the steel, it is important that information be available on the ranges of temperature and composition in which precipitated phases are stable. For this reason, and also to achieve desired precipitation characteristics using the minimum amounts of expensive precipitating elements such as niobium, titanium, vanadium, etc., it is helpful to cany out prior calculations of the stability of precipitates in steels of different compositions. 

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