Abstract: An acoustic sensor for monitoring machining processes in machining tools, e.g. grinding machines, includes a stationary unit, or stator (21) and a rotating unit, or rotor (23), the latter being coupled, for instance, to the grinding wheel and rotating with it. The rotor includes a support (45;45?) and a piezoelectric transducer (33). The position of the transducer is defined and locked without using glues by means of mechanical elements (48, 53, 54; 63, 64; 74, 78) that may include elastic elements such as springs. The rotor also includes a printed circuit board (55), connected to the piezoelectric transducer, with a charge amplifier (37) for amplifying the output signal of the piezoelectric transducer. The rotor is electrically coupled to the stator by means of transformer type couplings (30, 31).

Abstract: An apparatus and a method are provided for checking a machining process of a machine tool, for example a grinding machine, to obtain information about the quantity of a material removed and the wear condition of a grinding-wheel. The apparatus comprises an acoustic sensor adapted to detect acoustic signals generated by contact between the grinding-wheel and the piece being machined, and a force-detecting sensor adapted to detect the force applied between the grinding-wheel and the piece during the machining. The method comprises processing signals provided by both sensors, defining time intervals on the basis of the signals of the acoustic sensor, and monitoring the signals of the force-detecting sensor in the time intervals.

Abstract: An acoustic sensor for monitoring machining processes in machining tools, e.g. grinding machines, includes a stationary unit, or stator (21) and a rotating unit, or rotor (23), the latter being coupled, for instance, to the grinding wheel and rotating with it. The rotor includes a support (45;45?) and a piezoelectric transducer (33). The position of the transducer is defined and locked without using glues by means of mechanical elements (48, 53, 54; 63, 64; 74, 78) that may include elastic elements such as springs. The rotor also includes a printed circuit board (55), connected to the piezoelectric transducer, with a charge amplifier (37) for amplifying the output signal of the piezoelectric transducer. The rotor is electrically coupled to the stator by means of transformer type couplings (30, 31).

Abstract: An apparatus and a method for checking the machining process of a machine tool, for instance a grinding machine (1), to get information about the quantity of the material removed and the wear condition of the grinding wheel (9). The apparatus includes an acoustic sensor (19) adapted to detect the acoustic signals generated by contact between the grinding-wheel and the piece (13) to be machined, and a force-detecting sensor (21) adapted to detect the force applied between grinding-wheel and piece during the machining. The method includes processing signals provided by both the sensors, to define time intervals (ti-tf) on the basis of the signals (SA) of the acoustic sensor, and to monitor the signals (SF) of the force-detecting sensor in the so-defined intervals.

Abstract: A linear inductive transducer (T) includes a pair of primary windings (1, 3), fed by means of a power supply unit (C; 11, 13), a pair of secondary windings (2, 4) and a magnetic core (8), movable with respect to the windings. The secondary windings are electrically connected at an intermediate connection point between the primaries, and the transducer provides an electric output signal (Vo) as the sum of two components (Vs, Vs′), both variable as the mutual position between the windings and the core changes, and that depend on variations of the inductance of the primary windings and mutual inductance between the primaries and the secondaries, respectively. According to a specific configuration, it is also possible, starting from a single structure and by varying, in substance, the power supply and the output connections, to attain a transducer (T′) with different functional characteristics (for example, of the differential transformer type, half bridge type, or of another type).