ACOUSTIC-EMISSION CHARACTERISTICS IN WOOD SANDING .2. EFFECTS OF SANDING PRESSURE AND SANDING DIRECTION ON ACOUSTIC-EMISSION IN BELT SANDING

The monitoring technique of wood machining processing is important for the automation of wood machining operations. Therefore, the developme nt of a sensing system for wood machining processing has been required . In this study, the acoustic emission (AE) signals generated during w ood sanding with a belt sander were measured. and the effects of sandi ng pressure and sanding direction on AEs were investigated. The result s obtained are summarized as follows: (1) In sanding parallel to the g rain, the AE count rate decreased rapidly in the early stage of sandin g, and then gradually approaches constant values for each grain size a nd each sanding pressure. This tendency is similar to the variation of the stock removal rate with sanding time. For each grain size of a sa nding bell, the AE count rates increase with increases of sanding pres sure. This increase is considered to be due to increases of both the n umber of cutting points and the amount of penetration of the abrasive grains. The variation of AE count rates and stack removal rates with t he grain size of the sanding belt showed contrary tendencies, because the former and the latter depend on the number of cutting points and t he amount of penetration of the abrasive grains, respectively. (2) In sanding perpendicular to the grain, stock removal rates and AE count r ates were greater than these values in sanding parallel to the grain. This fact was estimated to be caused by the differences in both the am ount of material removed and the chip formation mechanism.