Duramold

Duramold on puupohjainen komposiittimateriaali, jossa sidosaineena käytetään fenolihartsia ja tarvittava kuitu saadaan koivusta. Duramoldin valmistamisessa on käytetty koivuviiluja, jotka on kyllästetty fenolihartsilla ja yhdistetty muotissa paineen alaisena ja 138 °C:n lämpötilassa hartsin kovettamiseksi.[1]

Fairchild P-46 on ensimmäinen duramold-komposiitista rakennettu lentokone.

Historia
Hughes H-4 Hercules "Spruce Goose" on lempinimestään huolimatta valmistettu enimmäkseen koivuviiluihin pohjautuvasta duramold-komposiitista.

Vuonna 1917 Henry L. Haskell patentoi menetelmän, jolla puun ja vedenkestävän liiman seoksesta saattoi tehdä muottiin lähes mielivaltaisen muotoisia esineitä. Tätä keksintöä hyödyntäviä tuotteita markkinoitiin nimillä Duromold, Plymetl ja Phemaloid.[2][3][4] Virginius E. Clark tutki puukomposiittien sopivuutta lentokoneiden rakenteisiin ja patentoi vuonna 1922 puukomposiittiin perustuvan lentokoneen siipirakenteen.[5][6] Fairchildille työskennellessään Clark sai valtuudet kehittää puukomposiitin käyttöä vaihtoehdoksi lentokoneiden kalliille alumiinirakenteille. Yhteistyössä Haskeliten kanssa Fairchild kehitti fenolihartsin ja koivuviilujen yhdistelmästä komposiittimateriaalin, jolle Clark antoi nimen Duramold.[7] Ensimmäinen pääosin duramoldista rakennettu lentokone on Fairchild F-46, jota rakennettiin vain yksi kappale.[8] Suurin koskaan enimmäkseen duramoldista rakennettu lentokone on Hughes H-4 Hercules.

Katso myös

Lähteet
  • Schatzberg, Eric: Wings of wood, wings of metal, s. 182–191. Princeton University Press, 1998. ISBN 0-691-08773-3. (englanniksi)

Viitteet
  1. Schatzberg, s. 183. Lainaus: "The Duramold process represented a synthesis of two lines of development in wood products: molded plywood and resin-bonded "improved" wood. Bag-molding techniques were not new to airplane construction, having been used quite successfully on the Lockheed Vega. But in contrast to the casein-glued Vega fuselage, Duramold required molding pressures as high as 100 pounds per square inch and temperatures up to 280 °F, which made the molding equipment more complicated. The Duramold process initially used a pressure bag placed over a steam-heated convex cast-iron die, which was similar to Haskelite's unsuccessful approach to molding fuselage panels in World War I (except for the pressure bag). Duramold also differed from earlier molded plywoods in its use of phenolic resins and thin veneers of 1/48 in. (0.5 mm) to 1/20 in. (1.3 mm) thickness, reminiscent of Kraemer's work at the DVL. These thin veneers were easily bent into the compound curvatures needed for streamlined surfaces. The Duramold process permitted dramatic increases in speed of production, even allowing for exaggerated claims."
  2. Imparato, Massimo: Eero Saarinen: L'unità organica nel progetto d'arredo - The organic unit in furniture design, s. 108. Lähdeviite 12. Gangemi Editore, 2015. ISBN 978-88-492-9845-1. (englanniksi) Lainaus: "Established in 1917 by Henry L. Haskell, the company patented a way to mold bonded plywood into "virtually" any shape using pressure and a unique waterproof glue. Advertised in differing forms as Duromold, Plymetl or Phemaloid, this product was ideal for applications requiring a strong yet lightweight construction material. It was widely used in boats, trains, airplane fuselages and automobile door planes, just to name a few."
  3. Haskelite Manufacturing Corporation (Hasko) Museum of Talking Boards. 1.11.2014. Viitattu 21.1.2016. (englanniksi) Lainaus: "Haskelite Manufacturing Corporation (1917-1958) perfected a way to mold bonded plywood into virtually any shape using pressure and H. L. Haskell's unique waterproof glue. Advertised in differing forms as Duromold, Plymetl, and Phemaloid, this product was ideal for applications that required a strong yet lightweight construction material. It was widely used in boats, trains, airplane fuselages and automobile door panels, just to name a few."
  4. Patentti U.S. 1343 450 Boot or shoe sole. Haskelite Manufacturing Corporation, Michigan. (Henry L. Haskell) Application 196 419, 1917-10-13. (1920-06-15). 3 s.
  5. Patentti U.S. 1552 112 Molded airplane wing. Dayton-Wright Company, Ohio. (Virginius E. Clark) Application 530 433, 1922-01-19. (1925-09-01). 6 s.
  6. Schatzberg, s. 182. Lainaus: "Clark's search for a rivetless construction quickly led him to molding techniques using resin-bonded plywood. In addition to his success as a designer of metal airplanes, Clark also had a background in plywood molding, having supervised the development of a molded plywood fuselage at McCook Field during World War I (see chapter two). Clark had himself obtained a patent on a molded wing structure in the early 1920s."
  7. Schatzberg, s. 182. Lainaus: "With support from Fairchild, Clark began working with the Haskelite Manufacturing Corporation and its head, George Meyercord, "one of the most fertile minds ... in the plywood field." It was quite natural that Clark and Fairchild would turn to Haskelite, given the company's experience with aircraft plywood and its role in developing resin-bonded plywood. The Fairchild and Haskelite companies jointly developed a bag-molding technique for producing airplane parts of phenolic plywood, termed "Duramold" by Clark."
  8. Fairchild 46-A (Clark GA-46 Duramold) Aviadesign. 25.5.2010. BIS Productions. Viitattu 21.1.2016. (englanniksi) Lainaus: "This handsome passenger transport was the idea of Col. Virginius E. Clark, Fairchild Corporate vice president of engineering. The fuselage was constructed according to the Haskelite bonded-plywood process, patented as Duromold and later changed to Duramold for incorporation. In fact the aircraft was a “proof of concept” design to explore the use of that process, which consisted in molded wood panels and structure, bonded together with a plastic resin under heat and pressure in an autoclave. A subsidiary company called Duramold aircraft company was created in 1937 to shepherd the project along."
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