RECOGNITION OF WOOD CUTTING CONDITIONS THROUGH CUTTING SOUNDS .1. EFFECTS OF TOOL SYSTEMS STIFFNESS AND TOOL WEAR ON THE GENERATION OF SOUND IN CUTTING PARALLEL TO THE GRAIN

To examine the possibility of in-process recognition of wood cutting c onditions and tool wear by cutting sounds, orthogonal cutting tests an d measurements of sounds during wood cutting were conducted in cutting parallel to the grain with a whirling disc-machine. Cutting tests wer e performed on six depths of cuts (0.025-0.5 mm), three stiffnesses of tool systems, and five edge recessions of tools (0-100 mum), keeping cutting speed at 1 m/s constant. Cutting sounds were measured in a fre quency range up to 70 kHz. The results are summarized as follows: 1) F undamental frequency of cutting sound almost agreed with the frequency of checked pitch calculated from both the pitch of checks on the surf aces of chips and cutting speed. It was therefore considered that the sound of fundamental frequency resulted from a change of cutting resis tance during wood cutting. 2) Frequency characteristic of a cutting so und was effected by the stiffness of the tool system and the depth of cut, and it was related to changes of chip formation and the natural f requency of the tool system. 3) Sound pressure level of a low-frequenc y range (0-20 kHz) decreased with increases of tool wear at small dept hs of cuts, and the frequency characteristic of a cutting sound was re lated to the condition of the chip formation. 4) Measuring of a wave f orm of a power spectrum and the sound pressure level of a specific fre quency range are promising for in-process recognition of chip formatio n and tool wear.