A preventive maintenance system of a machine tool capable of making determination of presence of an abnormality mechanically and automatically, which has conventionally been performed on the basis of the feeling of an operator and detecting an abnormality more accurately in an earlier stage is provided. The preventive maintenance system includes: a vibration detection unit attached to a mechanism of a machine tool to detect vibration; a sound detection unit that detects acoustic waves produced when a work is machined by the machine tool; a servo motor current value detection unit that detects a current value of a servo motor; an abnormality determination unit that compares the vibration, the acoustic waves, and the current value of the servo motor during operation of the machine tool with vibration data, acoustic wave data, and current value data in a normal state set in advance to determine presence of an abnormality in the mechanism of the machine tool; and a detection start/end command setting unit that adds commands for a detection start point and a detection end point of at least one of the vibration, the acoustic waves, and the current value of the servo motor to a machining program.

A preventive maintenance system of a machine tool capable of making determination of presence of an abnormality mechanically and automatically, which has conventionally been performed on the basis of the feeling of an operator and detecting an abnormality more accurately in an earlier stage is provided. The preventive maintenance system includes: a vibration detection unit attached to a mechanism of a machine tool to detect vibration; a sound detection unit that detects acoustic waves produced when a work is machined by the machine tool; a servo motor current value detection unit that detects a current value of a servo motor; an abnormality determination unit that compares the vibration, the acoustic waves, and the current value of the servo motor during operation of the machine tool with vibration data, acoustic wave data, and current value data in a normal state set in advance to determine presence of an abnormality in the mechanism of the machine tool; and a detection start/end command setting unit that adds commands for a detection start point and a detection end point of at least one of the vibration, the acoustic waves, and the current value of the servo motor to a machining program.

In one aspect, the present invention relates to a contour checking device for calculating path deviations from a target path of a cutting head of a laser machine tool. The contour checking device comprises a reference texture interface for reading a reference texture along the target path, which is defined in particular for cutting a contour, a controller, which is intended for controlling the laser machine tool in such a way that the cutting head traverses the target path; at least one camera, wherein the controller for controlling the at least one camera is intended for continuously capturing overlapping frames of the reference texture along the traversed path; a processor, which is intended for executing an image processing algorithm for reconstructing the trajectory traversed by the cutting head from the captured overlapping frames of the reference texture; and wherein the processor is intended for calculating deviations between the reconstruction of the path traversed by the cutting head and the target path. The contour checking device also comprises an output interface, which is intended for outputting the calculated deviations.