胶合板的英文介绍

Plywood.r. iSoftwood plywood made from spruceContents1 History2 Structural characteristics3 Typeso3.1 Softwood plywoodo3.2 Hardwood plywood3.2.1 Tropical plywoodo3.3 Special-purpose plywood 3.3.1Aircraft plywood 3.3.2Decorative plywood (overlaid plywood) 3.3.3Flexible plywood 3.3.4Marine plywood 3.3.5Other plywoods4 Production5 Sizes6 Grades7 Applicationso7.1 Softwood plywood applicationso7.2 Hardwood (Birch) plywood applicationso7.3 Tropical plywood applications8 See also10 External linksPlywood is a manufactured wood panel from the family of manufactured boards (such as MDF, Chipboard etc.) made from th in sheets of wood ven eer. Plywood layers (called ven eers or plys) are glued together, with adjace nt plies hav ing their wood grain rotated relative to adjace nt layers up to 90 degrees.All plywoods bind res in and wood fiber sheets (cellulose cells are long, str ong and thin) to form a composite material. This alternation of the grain is called cross-graining and has several importa nt ben efits: it reduces the tendency of wood to split whe n n ailed at the edges; it reduces expansion and shrinkage, providing improved dimensional stability; and it makes the strength of the panel con siste nt across all directi ons. There is usually an odd nu mber of plies, so that the sheet is balaneedthis reduces warp ing. Because plywood is bon ded with gra ins running aga inst one another and with an odd number of composite parts, it is very hard to bend it perpendicular to the gra in directi on of the surface ply.Smaller thinner plywoods and lower quality plywoods (see Average-quality plywood photo below and right) may only have their plys (layers) arra nged at right an gles to each other, though many better quality plywood products will by design have five plys in steps of 45 degrees (0, 45, 90, 135, and 180 degrees), giv ing stre ngth in multiple axes. The highest quality specialty plywoods ofte n have plys at 30 degrees (0, 30, 60, 90, 120, 150, and 180 degrees) in seven layers, or have nine layers with two layers of 45 and 135 degrees in the sandwich. The smaller the step rotations the harder it is to manufacture, increasing manufacturing costs and consequently retail price.HistoryIn 1797 the Englishman Sir Samuel Bentham applied for patents covering several machines to produce ven eers. In his pate nt applicati ons, he described the con cept of lam in at ing several layers of veneer with glue to form a thicker piece 一 the first description of what we now call plywood1】 Samuel Bentham was a British naval engineer with many ship-building inventions to his credit. Veneers at the time of Bentham were Flat sawn, Rift sawn or Quarter sawn; i.e. cut along or across the log manually in different angles to the grain and thus limited in width and length.About fifty years later Immanuel Nobel, father of Alfred Nobel, realized that several thinner layers of wood bon ded together would be str on ger tha n one sin gle thick layer of woodiatati。n needed； un dersta nding the in dustrial pote ntial of laminated wood he inven ted the rotary lathe 丄 atat。n neededThere is little record of the early implementation of the rotary lathe and the subsequent commercialization of plywood as we know it today, but in its 1870 edition, the French dicti on ary Robert describes the process of rotary lathe ven eer manu facturi ng in its entry Deroulage.2 Once can thus presume that rotary lathe plywood manufacture was anestablished process in France in the 1860s. Plywood was introduced into the United States in 1865【3 and in dustrial production started shortly after. In 1928, the first sta ndard-sized 4 ft by 8 ft (1.2 m by 2.4 m) plywood sheets were in troduced in the Un ited States for use as a gen eral buildi ng material4】As for artists use of plywood as support for easel paint,ingslacing traditional canvas or cardboard; a recent JSTOR article has brought to light that ready-made artist boarcfor oil painting in three-layered plywood (3-ply) were produced and sold in New York as early as 1880.5 It is evide nt that there was an applicati on precede nt going back several years. Whe n con sider ing the adva ntage of simply cutt ing raw board to wan ted measure, one might safely assume that the progressive phalanges among late 19th century French artists embraced this new support for their paintings from the very beginning of the national manufacture (1860s).Structural characteristicsA typical plywood panel has face veneers of a higher grade than the core veneers. The principal fun cti on of the core layers is to in crease the separati on betwee n the outer layers where the bending stresses are highest, thus in creas ing the pan els resista nee to bending. As a result, thicker pan els can spa n greater dista nces un der the same loads. In bending, the maximum stress occurs in the outermost layers, one in tension, the other incompression. Bending stress decreases from the maximum at the face layers to n early zero at the cen tral layer.Shear stress, by con trast, is higher in the cen ter of the pan el, and zero at the outer fibers.TypesAverage-quality plywood with show veneerBirch plywoodDifferent varieties of plywood exist for different applications:Softwood plywoodSoftwood panel is usually made either of cedar, Douglas fir or spruce, pine, and fir (collectively known as spruce-p in e-fir or SPF) or redwood and is typically used for con structi on and in dustrial purposes6】The most com mon dime nsion is 1.2m x 2.4m or the slightly larger imperial dime nsion of 4 feet x8 feet. Plies vary in thick ness from 1.4 mm to 4.3 mm. The amount of plies depe nds on the thickness and grade of the sheet but at least 3. Roofing can use the thinner 5/8 (15 mm) plywood. Subfloors are at least 3/4 (18 mm) thick, the thick ness depe nding on the dista nee betwee n floor joists. Plywood for flooring applications is often tongue and groove; This prevents one board from movi ng up or dow n relative to its n eighbor, so provid ing a solid feeli ng floor whe n the joi nts do not lie over joists. T&G plywood is usually found in the 1/2 to 1 (12 25 mm) range Hardwood plywoodUsed for demanding end uses. Birch plywood is characterized by its excellent strength, stiffness and resista nee to creep. It has a high pla nar shear stre ngth and impact resista nee, which make it especially suitable for heavy-duty floor and wall structures. Oriented plywood construction has a high wheel-carry ing capacity. Birch plywood has excelle nt surface hard ness, and damage- and wear-resista nee7】Tropical plywood Tropical plywood is made of mixed species of tropical wood. Originally from the Asian region, it is now also manu factured in Africa n and South America n coun tries. Tropical plywood is superior to softwood plywood due to its density, strength, evenness of layers, and high quality. It is usually sold at a premium in many markets if manufactured with high standards. Tropical plywood is widely used in the UK, Japa n, Un ited States, Taiwa n, Korea, Dubai, and other coun tries worldwide. It is the preferred choice for construction purposes in many regions due to its low cost. However, many coun tr ies fores ts have been -bvevested, in clud ing the Philipp in es, Malaysia and Indon esia, largely due to the dema nd for plywood producti on and export.Special-purpose plywoodCerta in plywoods do not have alter nati ng plies. These are desig ned for specific purposes.Aircraft plywoodHigh-stre ngth plywood also known as aircraft plywood, is made from mahoga ny an d/or birch, and uses adhesives with in creased resista nee to heat and humidity. It was used for several World War II fighter aircraft. Although the British-built Mosquito bomber, nicknamed The Wooden Wonder, was con structed of a plywood mono coque, this was formed in moulds from in dividual ven eers of birch, balsa and birchickaf/o n needed, rather tha n mach ined from pre-lam in ated plywood sheets.Structural aircraft-grade plywood is more com mon ly manu factured from Africa n mahoga ny or American birch veneers that are bonded together in a hot press over hardwood cores of basswood or poplar. Basswood is another type of aviation-grade plywood that is lighter and more flexible than mahogany and birch plywood but has slightly lessQa。n needed structural strength.Allwhere? aviation-grade plywood is manufactured to specifications outlined in MIL-P-607, which calls for shear testing after immersion in boiling water for three hours to verify the adhesive qualities betwee n the plies and meets specificati ons.Decorative plywood (overlaid plywood)Usually faced with hardwood, including ash, oak, red oak, birch, maple, mahogany, Philippine mahogany (often called lauan, luan or meranti and having no relation to true mahogany), rose wood, teak and a large number of other hardwoods. However, Formica, metal and resin-impreg nated paper or fabric bon ded are also added on top of plywood at both side as a kind of ready for use in the decoration field. This plywood is a lot easier to dye and draw on than any other plywoods.冋 exible plywoodFlexible plywood is very flexible and is designed for making curved parts. In the UK this is sometimes known as Hatters Ply as it was used to make stovepipe hats in Victorian timescao,n needed. It is also often referred to as Bendy Ply due to its flexibility. However these may not be termed plywood in some countries because the basic description of plywood is layers of veneered wood laid on top of each other with the gra in of each layer perpe ndicular to the gra in of the n ext. I n the U.S., the terms Bender Board and Wiggle Board are commonly used.Marine plywoodMarine plywood is manufactured from durable face and core veneers, with few defects so it performs lon ger in humid and wet con diti ons and resists delam in ati ng and fun gal attack. Its construction is such that it can be used in environments where it is exposed to moisture for long periods. More recently, tropical producers have become dominant in the marine plywood market. Okoume from Gabon is now the accepted standard for marine plywood, even though the wood is not very resista nt to rot and decay. Each wood ven eer will be from tropical hardwoods, have negligible core gap, limiting the chance of trapping water in the plywood and hence providing a solid and stable glue bon d. It uses an exterior Water and Boil Proof (WBP) glue similar to most exterior plywoods.Marine plywood can be graded as being compliant with BS 1088, which is a British Standard for mari ne plywood. There are few in ter nati onal sta ndards for grad ing mari ne plywood and most of the standards are voluntary. Some marine plywood has a Lloyds of London stamp that certifies it to be BS 1088 compliant. Some plywood is also labeled based on the wood used to manufacture it. Examples of this are Okoume or Meranti.Marine plywood is frequently used in the construction of docks and boats. It is much more expensive than standard plywood: the cost for a typical 4-foot by 8-foot 1/2-inch thick board is roughly $75 to $100 U.S. or around $2.5 per square foot, which is about three times as expensive as sta ndard plywood.Other plywoodsOther types of plywoods in clude fire-retarda nt, moisture-resista nt, sig n-grade and pressure-treated. However, the plywood may be treated with various chemicals to improve the plywoods fireproofi ng. Each of these products is desig ned to fill a n eed in in dustry.ProductionPlywood producti on requires a good log, called a peeler, which is gen erally straighter and larger in diameter than one required for processing into dimensioned lumber by a sawmill. The log is laid horiz on tally and rotated about its long axis while a long blade is pressed into it, caus ing a thin layer of wood to peel off (much as a con ti nu ous sheet of paper from a roll). An adjustable no sebar, which may be solid or a roller, is pressed against the log during rotation, to create a gap for veneer to pass through between the knife and the nosebar. The nosebar partly compresses the wood as it is peeled; it controls vibration of the peeling knife; and assists in keeping the veneer being peeled to an accurate thick ness. In this way the log is peeled into sheets of ven eer, which are the n cut to the desired oversize dime nsions, to allow it to shr ink (depe nding on wood species) whe n dried. The sheets are the n patched, graded, glued together and the n baked in a press at a temperature of at least 140 (284 F), and at a pressure of up to 1.9 MPa (280 psi) (but more commonly 200 psi) to form the plywood pan el. The panel can the n be patched, have minor surface defects such as splits or small knot holes filled, re-sized, sanded or otherwise refinished, depending on the market for which it is inten ded.Plywood for in door use gen erally uses the less expe nsive urea-formaldehyde glue, which has limited water resista nee, while outdoor and mar in e-grade plywood are desig ned to withsta nd rot, and use a water resista ntphe no l-formaldehyde glue to preve nt delam in ati on and to retain stre ngth in high humidity.The adhesives used in plywood have become a point of concern. Both urea formaldehyde and phe nol formaldehyde are carc inogenic in very high concen trati ons. As a result, many manu facturers are tur ning to low formaldehyde-emitt ing glue systems, deno ted by an E rat ing (E0 possess ing the lowest formaldehyde emissi on s). Plywood produced to E0 has effectively zero formaldehyde emissi on s.8In addition to the glues being brought to the forefront, the wood resources themselves are beco ming the focus of manu facturers, due in part to en ergy con servati on, as well as con cer n for natural resources. There are several certificati ons available to manu facturers who participate in these programs. Forest Stewardship Council (FSC),Leadership in Energy and Environmental Design (LEED), Sustainable Forestry Initiative (SFI), and Greenguard are all certification programs that en sure that producti on and con structi on practices are susta in able. Many of these programs offer tax ben efits to both the manu facturer and the end user9】SizesThe most com mon ly used thick ness range is from 0.14 to 3.0 in (0.36 to 7.6 cm). The sizes of the most commonly used plywood sheets are 4 by 8 ft (1.2 by 2.4 m). Width and length may vary in 1 ft (30 cm) in creme nts.In the Un ited States, the most com mon ly used size is 4 ft by 8 ft or 5 ft by 5 ft.10Sizes on specialised plywood for concrete forming range from 6 to 21 mm, and a multitude of formats exist, though 15x750x1500mm is very com monly used.GradesGrad ing rules differ accord ing to the coun try of orig in. Most popular sta ndard is the British Stan dard(BS) and America n Stan dard (ASTM). Joyce (1970), however, list some gen eral in dicati on ofgrad ing rules:11GradeDescriptionAFace and back veneers practically free from all defects.A/BFace veneers practically free from all defects. Reverse veneers with only a fe small knots or discolorations.A/BBFace as A but reverse side permitting jointed veneers, large knots, plugs, etcBBoth side veneers with only a few small knots or discolorations.B/BBFace veneers with only a few small knots or discolorations. Reverse side permitting jointed veneers, large knots, plugs, etc.BBBoth sides permitting jointed veneers, large knots, plugs, etc.WGGuaranteed well glued only. All broken knots plugged.XKnots, knot holes, cracks, and all ot her defec ts perm itt ed.JPIC Sta ndardsGradeDescriptionBB/CCFace as BB, back as CC. BB as very little knots of less than 1/4 inches, sligh discoloration, no decay, split and wormholes mended skillfully, matched colors no blister, no wrinkle. Most popular choice for most applications.ApplicationsPlywood is used in many applicati ons that n eed high-quality, high-stre ngth sheet material. Quality in this con text means resista nee to crack ing, break ing, shr in kage, twist ing and warp ing.Exterior glued plywood is suitable for outdoor use, but because moisture affects the stre ngth of wood, optimal performanee is achieved in end uses where the woods moisture content remains relatively low. On the other hand, subzero conditions dont affect plywoods dimensional or strength properties, which makes some special applicatio ns possible.Plywood is also used as an engin eeri ng material for stressed-sk in applicati on s. It has bee n used for mari ne and aviati on applicatio ns since WWII. Most no table is the British de Havilla ndMosquito bomber, which was primarily made using a moulded san dwich of two layers of birch plywood around a balsa core. Plywood was also used for the hulls in the hard-chine Motor Torpedo Boats (MTB) and Motor Gun Boats (MGB) built by the British Power Boat Company and Vospers. Plywood is currently successfully used in stressed-skin applications . The America ndesigners Charles and Ray Eames are famous for their plywood-based furniture, as is Finnish Architect Alvar Aalto and his firm Artek, while Phil Bolger is famous for designing a wide range of boats built primarily of plywood.Plywood is often used to create curved surfaces because it can easily bend with the grain. Skateboard ramps ofte n utilize plywood as the top smooth surface over bent curves to create tran siti on that can simulate the shapes of ocea n waves.Softwood plywood applicationsTypical end uses of spruce plywood are: Floors, walls and roofs in house con structi ons Wind brac ing pan els Vehicle in ter nal body work Packages and boxes FencingThere are coating solutions available that mask the prominent grain structure of spruce plywood. For these coated plywoods there are some end uses where reas on able stre ngth is n eeded but the light ness of spruce is a ben efit e.g.: Con crete shutter ing pan els Ready-to-pa int surfaces for con structi onsHardwood (Birch) plywood applicationsPhe nolic-film Coated birch plywood is typically used as a ready-to-i nstall comp onent e.g.: Pan els in con crete form work systems Floors, walls and roofs in tra nsport vehicles Container floors, Floors subjected to heavy wear in various build ings and factories, Scaffold ing materials(Wire or other styles of impri nting available for bett er tracti on)Birch plywood is used as a structural material in special applicatio ns e.g.: Wind turb ine blades In sulati on boxes for Liquefied Natural Gas (LNG) carriersSmooth surface and accurate thick ness comb ined with the durability of the material makes birch plywood a favorable material for many special end uses e.g.: High-e nd loud speakers Die-cutt ing boards Support ing structure for parquet Playgro und equipme nt Fur niture Signs and fen ces for dema nding outdoor advertis ing Musical in strume nts Sports equipme ntTropical plywood applicationsTropical plywood is widely available from the South-East Asia regi on, mai nly from Malaysia and Indon esia. Tropical plywood boasts premium quality, and stre ngth. Depe nding on mach in ery, tropical plywood can be made with high accuracy in thick ness, and is a highly preferable choice in America, Japa n, Middle East, Korea, and other regi ons aro und the world. Common plywood Con crete panel Floor base Structure panel Container floor ing Lam in board Lam in ated Ven eer Lumber (LVL)