The Study of Deformations in Laminated Wood Being Compressed by a Mould with Various Thickness

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UDС

674.093.026

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Abstract

Relief plywood has a volumetric pattern on its front surface, which allows us to use it as facing material. At relief plywood glueing we use a mould with various cross-section thickness, which makes the pressure on the veneer package at mould projections and hollows different. Consequently, the front side of relief plywood after glueing has a raised pattern which is the reverse photographic image of the mould pattern. The research aimed to establish the deformations at relief plywood glueing. The objective was to set the parameters of glueing mode, allowing us to predict the thickness of relief plywood. The author used the method of single-factor and two-factor experiments according to Box-Behnken design. To find the optimal parameters of this mode the author used the gradient method. Studying the time-deformation change of veneer package, the auhor established that during the first 2 minutes the deformation is increasing dramatically. Continued pressuring does not increase the deformation significantly. Thus, when gluing relief plywood the author recommends using pressure diagram stating that duration of exposure to the maximum pressure is 25 % of the total duration of pressuring. Plywood thickness after glueing depends on residual deformation, which, in its turn, depends on the basic parameters of glueing mode: pressure and duration of exposure to pressure. It was found that compacting pressure rising from 2.0 to 5.0 MPa makes residual deformation of outer and inner layers increase drastically. Further rise in compacting pressure from 5.0 to 8.0 MPa does not produce any significant increase in residual deformation. Thus, the optimal parameters of relief plywood gluing are the pressure P = 3.3 MPa and duration of gluing t = 5 min. The residual deformation of plywood in the areas of mould projections at these values are 38 %.

Authors

А.А. Lukash, Candidate of Engineering, Associate Professor

Affiliation

Bryansk State Engineering and Technological Academy

Keywords

deformation, wood, pressure, temperature, compressing, glueing, mould.

References

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