Study On Chinese Fir For Glulam Products Key Technology Research

Using the fast-growing Chinese fir as the research object,this thesis aim at discussing the key techniques of the manufacture of Chinese fir glulam by the poly vinyl acetate-isocyanate adhesive.The research content includes the following three aspects:1)Grading laminates visually,then measuring the ring density,the dry density,the elastic modulus and the bending strength of Chinese fir to determine the mechanical properties of laminates;Finally,the reliable grade method is obtained;2)Research on the effort of different finger parameters to the mechanical properties of Chinese fir laminates;3)Research on the effort of different factors(i.e.,the bonding pressure,the bonding time,the exposure time of bonding surface and the precision sanding of gluing surface)to the double compressed laminate to obtain the better gluing technology.Through the above research,we can conclude the better technology of Chinese fir glulam as bellows:l)The current visual grade method is not suitable to grade the artificial Chinese fir;The mechanical elastic modulus grade method can grade Chinese fir with the reliable performance;2)The better finger jointing technology of the artificial Chinese fir is listed as bellows:the model of the cutter is 4.2 × 160-40 with the vertical finger joint,the fitting degree is 0.20 mm,the finger pressure is 3 MPa-5 MPa;3)The best technology of poly vinyl acetate-isocyanate adhesive to manufacture the Chinese fir laminate is at the condition of 1 MPa end pressure,bonding time is 120 min,no sanding,exposure time should be as short as possible.