US 5,773,949 A · Cutter fracture detecting system

Abstract

A cutter fracture detecting system is capable of detecting a fracture of a cutter highly accurately which may occur even when no substantial loads are imposed on a rotating axis and a cutter feed axis of a machine tool. A rotating axis disturbant load torque estimating unit (1) and a moving axis disturbant load torque estimating unit (2) monitor disturbant load torques on a spindle and an axis with respect to which a workpiece and a cutter move relatively to each other, and still axis disturbant load torque estimating units (3, 4) also monitor disturbant load torques on axes with respect to which the workpiece and the cutter do not move relatively to each other. A comparing unit (5) determines that the cutter is fractured based on the disturbant load torques estimated by the disturbant load torque estimating units. When a cutter fracture is detected, the machine tool is stopped by a machine shutdown command unit (6).

Claims9

Dependent claims

A cutter fracture detecting system for a numerically controlled machine tool in which a workpiece and a cutter move relatively to each other, the cutter fracture detecting system comprising:

still axis disturbant load torque estimating means for estimating a disturbant load torque acting on at least one axis on which the workpiece and the cutter do not move relatively to each other;
comparing means for comparing the disturbant load torque estimated by said still axis disturbant load torque estimating means with a predetermined reference torque;
and
machine shutdown command means for outputting a command signal to stop the numerically controlled machine tool depending on a result of the comparison performed by said comparing means.

1 more element

A cutter fracture detecting system comprising:

still axis disturbant load torque estimating means for estimating a disturbant load torque acting on at least one axis on which the workpiece and the cutter do not move relatively to each other:
rotating axis disturbant load torque estimating means for estimating a disturbant load torque acting on a spindle which rotates the cutter;
moving axis disturbant load torque estimating means for estimating a disturbant load torque acting on at least one feed axis which controls relative movement of the workpiece and the cutter;
comparative decision means for comparing a combined torque produced by combining disturbant load torques estimated by said still axis disturbant load torque estimating means, said rotating axis disturbant load torque estimating means and said moving axis disturbant load torque estimating means with a predetermined reference torque, and determining that said cutter is fractured when said combined torque exceeds said reference torque;
and
machine shutdown command means for outputting a command signal to stop the numerically controlled machine tool depending on a result of the comparison performed by said comparative decision means.

3 more elements

Dependencies are inferred from the claim text.

Cutter fracture detecting system

Life of this patent

Cutter fracture detecting system

Life of this patent

Abstract

Claims9