ANÁLISIS DE LOS FACTORES QUE INTERVIENEN EN EL PROCESO DE PRENSADO DEL TRIPLAY.

Abstract

Plywood quality and productivity is determined by the pressing process. To optimize it, an understanding of the parameters involved in the production of boards is required, as wood, adhesive, temperature, pressure. The resins for plywood (urea and phenol formaldehyde) cured at high temperatures, the moisture of the veneer and the adhesive, besides delaying the polimerization of the resin, produces vapor pressure that tends to separa te the veneer through delaminations or "blows". The present study was carried out to determine the distribution of temperature in the glue lines, the vapor pressure in the lamina te and the effect of the platen load on plywood compaction.
Douglas fir veneer with 6, 12 and 16% of moisture content (M.C.), a press with 2' x 2' platens heated with stearn and phenol tormaldehyde resin were used. Temperature, vapor pressure and compaction of plywood during pressing were measured with digital to analog convertors using thermocouples, hypoderrnic tubes and a linear variable differential transducer (L VDT). A constant pressing temperature of 148:8ºC (300ºF) and platen loads of 100, 125 and 175 psi were applied. Plywood was made up of 5 layers, with a pressing time of 1 000 seconds. Data collection and process control was achieved with a personal computer.