Definition of types of lumber (radial, tangential)

The possibility of using ultrasound to determine the saw cut types of lumber is considered. Depending on the cutting pattern (set), lumber can be radially or tangentially sawn. The use of a certain type of lumber, the principles of their symmetrical arrangement in glued timber structures and other conditions depend on the requirements for finished products. Visual sorting of lumber by the direction of annual layers at the end in flow production is impractical, since it does not ensure the required level of labor productivity. A high degree of reliability in the diagnostics of solid wood is shown by the temporary shadow method of acoustic control. In the framework of the studies, a frequency of 2.5 MHz was used. When sounding wood, due to its anatomical structure, a number of features of the diagnostics itself arise, which allow expanding the possibilities of using the method. Such features include different speeds of ultrasound passage depending on the density of the wood, shifting the ultrasonic signal, the need for a reasonable selection of frequency, etc. During acoustic diagnostics, depending on the sawing option of lumber, different deviations of the ultrasonic signal are observed. The conducted studies show that the signal shift is most likely due to its movement along ribbon-like formations of parenchymatous cells, directed radially with respect to the wood growth layers – medullary rays. The results of the studies, the values of the signal shift angles depending on the type of lumber are given. Signal shift by an angle in the range from 25° to 53° relative to the emitter is typical for radial lumber, and signal shift by an angle of less than 25° determines tangential lumber.

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