Tube winding

After the waterwaH tubes deHver the saturated steam back into the top of the boHer dmm, moisture is separated out by a series ofbaffl.es, steam separators, and cormgated screens. The water removed drops down into the hot water contained in the steam dmm. The steam travels out through either a dry pipe, which leads to a superheater header, or a series of superheater tubes that connect directiy into the top of the steam dmm. The superheater tubes wind back into the top of the furnace and/or a hot flue-gas backpass section, next to the economizer, where heat from the combustion gases exiting the furnace superheats the steam traveling through the tubes. 

Figure 23.20. Three-roller tube winding machine. (After Brown )...

Adhesive, Dextrin (Spiral Tube Winding for Ammunition Containers) US Spec MIL-A-13374C (June 1969)... 

The type of tubing used for constructing the manifold should always be specified but less emphasis should be given to manifold components outside of the analytical path. There are different types of reactor (see 6.2.3) and they should be specified. The coiled reactor is by far the most common, and no further information means that this kind of reactor is used. Length and inner diameter of the tubing, winding diameter of the coiled reactor and the presence of different accessories (mixing chambers, solid-phase mini-columns, immobilised enzymes and connectors) in the analytical path should be reported. 

Other synthetic emulsions include acrylics, which are widely used in pressure-sensitive adhesives for labels, polyurethanes, and synthetic rubbers. Sodium silicate was once widely used in paper packaging, but its only remaining major use is in tube winding, especially for large drums or cores. 

Because of the need to remove water, most applications for aqueous adhesives are with materials that would allow transmission of water vapor. Hence the major uses are with paper, wood and fabric, either as binders or laminating adhesives. Typical applications of emulsion adhesives include the following remoistenable gummed tape, tube winding, box manufacture, plywood manufacture, woodworking, bookbinding, abrasives manufacture, and as textile adhesives. 

A CNC control system with brushless motors has been used by specialist processors to re-engineer a filament tube-winding machine for fast, accurate and consistent performance. The control made the unit capable of distributing resin-impregnated fibers evenly around the rotating mandrel at programmable feed rates of 60 m/min irrespective of the pitch of the filament. The vertical machine produce tubes up to 3 m finished length and 760 mm inside diameter. 

The rotating tube winds the nylon strand, which continues to form at the interface in the beaker. 

Dextrins have many applications, with adhesives being their primary market (11,96). Dextrins are used as adhesives for case and carton sealing. For this application, borax is often added to the dextrin to add stability and increase viscosity. Dextrins are added to adhesives used in the laminating of products such as paperboard and shipping containers. The paper industry adds dextrins in adhesives for tube winding and bag adhesives. Library pastes, bottle label adhesives, envelop adhesives, gummed tape, and wall covering adhesives all benefit fiom dextrin addition. 

Tube Winding. Mainly dextrin adhesives are used and/or plasticized homopoly-meric poly(vinyl acetate) emulsions, but glutin glues are also used in special cases. 

Dextrins are frequently formulated with borax, sodium metaborate, boric acid, or caustic in different proportions to give good tack and higher stable viscosities at moderate concentrations. The pH of the formulations is about 9.0 in most cases. Borated dextrins find use in case sealing, carton sealing, tube winding, and laminating. 

Tube winding is either spiral (a continuous winding where adhesive is applied to outer plies as they are wrapped on a cylindrical mandrel), or convolute (where the sheet is as wide as the mandrel is long, and the mandrel wraps the sheet over itself). The tube is removed from the mandrel by a pusher arm. Convolute adhesives are usually used cold, while spiral adhesives may be used at 131°F (55°C). Many starch products may be used, but 50% solids borated dextrins are common, as seen in Table 4. 

Tube winding Tough, fast bond Borated dextrin 48 2500 (RV 4/20/80)... 

The tackified polyvinyl alcohols, introduced in the early 1960s, rapidly replaced starch/urea formaldehyde adhesives in solid fiber laminating and dextrine, compounded polyvinyl acetate and sodium silicate adhesives in spiral tube winding. The new adhesives demonstrated superior adhesion over silicates and dextrines to a wide variety of paper substrates. These adhesives reduce warp in solid fiber laminating and shrinkage in spiral tubes because of the low adhesive application rate and, thus, low amount of water added to the laminations. The low application rate and low resin level also made these adhesives very economical. 

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