DEVICE FOR RETAINING AXIAL TOOL IN MACHINE-TOOL SPINDLE Russian patent published in 1994 - IPC

FIELD: machine-tool engineering. SUBSTANCE: device has interconnected driven and driving members in the form of housing 1 and sleeve 2 with sensor 3 in the form of power source connected electrically with heating element 4 located on external surface of sleeve 2 inside space 5. Tool is protected against overloads with the use of fusible substance with constant low-melting point, which is lower than limit permissible working temperature of lubricant used in bearings 6. Used as low-melting point substance is Wood alloy enclosed in sealed space 5. Initially Wood alloy is hard. When machine-tool is started, housing 1 begins to rotate together with sleeve 2 carrying cutting tool 9. When cutting tool 9 becomes blunt, axial cutting force grows and causes excessive pressure on sensor 3, for example ring manufactured of piezoelectric ceramics. Electric power arising in sensor 3 under action of applied force is fed to heating element 4, which makes Wood alloy melt. As a result torque transmission to sleeve 2 will be interrupted and sleeve will stop rotating. Termination of force action results in decrease of voltage on sensor 3 and in setting of alloy and consequently in resumption of rotation of sleeve 2 and cutting tool 9. EFFECT: improved safety of machine-tool operation. 2 cl, 1 dwg