Method and apparatus for determining the nodosity of a wooden plank

A method for determining the nodosity of a wooden plank having a main direction of extension, a lateral surface (4) substantially parallel with the main direction of extension and two end surfaces (5) substantially transversal to the main direction of extension, comprising the operating steps of:

• observing the lateral surface (4) of the wooden plank (1) to identify its zones (7) corresponding to knots (6);
• assessing the overall extent of the knots (6) inside the plank (1) and the relative volume;
• and
• determining the nodosity as a ratio of the volume occupied by the knots (6) to the overall volume of the plank (1) or the remaining volume of the plank (1);
• the method being characterised in that the step of assessing the extent of the knots (6) in turn comprises the operating steps of:
• inspecting at least one end surface (5) of the plank (1) to detect at this end surface the development curves of the growth rings (3) belonging to the log (2) from which the wooden plank (1) was obtained;
• based on the trend of the development curves of the rings (3), estimating the position in space, relative to the plank (1), of the longitudinal axis (8) of the log (2) from which the plank (1) was obtained;
• assuming that each knot (6) identified on the outer surface extends, inside the log (2) from which the plank (1) was cut, as a conical body extending radially from the longitudinal axis (8) with its vertex on the longitudinal axis, and passing through the zone (7) of the lateral surface (4) of the plank (1) corresponding to the knot (6);
• and
• calculating the volume of the knots (6) as the intersection between said bodies and the plank (1).