HARD WOOD CHIP CEMENT BOARD AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To specify a wood amount of a hard wood chip cement board in the surface part and improve the surface property and nailing property of the board, by dropping a mixture consisting essentially of cement and wood chips into a forming chamber while blowing air thereto to classify the mixture and spraying and depositing the mixture onto a lower template. SOLUTION: A mixture consisting essentially of cement and wood chips is dropped onto a slant sieve 22. At the time, air is blown from an air discharge port 24 of a blowing duct 23 thereto to classify the mixture. Fine and light raw material is deposited on a lower template 11 on the upstream side and a coarse and heavy raw material is deposited on the middle stream side to provide deposites 13. Further, a mixture 14 having the same composition is carried to the downstream end part and dropped to a slant sieve 32. Air is blown to the mixture to classify the mixture and the coarse and heavy raw material is deposited on the lower template 11 on the middle stream side and fine and light raw material is deposited on the downstream side. As a result, the finest and lightest raw material is deposited on the uppermost face of the deposites 13 and dense surface part is obtained on the rear face. The air velocity is set to about 10-20m/sec so that wood amount of the surface part becomes 8-14wt.%.