Abstract: The invention relates to a method of active attenuation of machine directon pressure pulsations in the stock fed into the headbox (10) of a paper or board machine in such a way that the pressure pulsations in the stock are measured and the water flow to be fed into the stock is controlled on the basis of the results of the measurement. The volume available for the stock flow is controlled by means of water flow changes. Pressure variations achieved by volume variations are arranged substantially in opposition to the pressure variations to be attenuated thus attenuating the pressure variations in the stock. The invention also relates to an apparatus for carrying out the above method. The apparatus comprises a sensor (6) or a set of sensors, on the basis of whose output signal/signals a regulator (7) has been arranged to automatically control the water flow to be fed into the stock by an adequately fast valve arrangement (1) moved by the controlling element (2) of the regulator (7).

Abstract: A method and an apparatus for sawing a piece of timber and particularly for edging a board. The piece of timber is brought to pass in its longitudinal direction through a measuring station and further, maintaining its position, to a sawing machine. The optimum width and sawing direction are determined by the measuring data obtained by means of measuring gates collected in the memory of a computer. The computer controls the sawing blades. The blades of the sawing machine are turned to take the desired sawing direction and are moved at an even speed in lateral direction during the sawing process. The apparatus comprises a conveyor for transferring the log of timber, a plurality of gates for measuring the optimum width and direction, a computer for collecting the data. The computer controls the blades so that during sawing, the sawing lines coincide with the edge lines of the calculated optimum board. The sawing machine is mounted on vibration dampers which act as springs.