Abnormality detection apparatus, abnormality detection method, and non-transitory computer readable recording medium

An abnormality detection method of detecting an abnormality of a ball screw provided in an injection molding machine, the abnormality detection method comprising:

• operating the injection molding machine to perform injection molding;
• detecting an alternating current of a motor for applying a driving force to the ball screw during operation of the injection molding machine;
• performing frequency analysis on a detected alternating current;
• and
• detecting an abnormality of the ball screw based on information related to a distribution of frequency components obtained by frequency analysis, and information related to a distribution of frequency components obtained by frequency analysis of an alternating current detected when the ball screw is normal, comprising:
• calculating a statistical distance between a statistic of the distribution of frequency components obtained by frequency analysis of the alternating current detected by a current sensor and a statistic of the distribution of frequency components obtained by frequency analysis of the alternating current detected when the ball screw is normal, and detecting an abnormality of the ball screw based on the calculated statistical distance.

A non-transitory computer readable recording medium storing a computer program for causing a computer to execute a process of detecting an abnormality of a ball screw provided in an injection molding machine, the computer program causing the computer to execute processes of:

• operating the injection molding machine to perform injection molding;
• detecting an alternating current of a motor for applying a driving force to the ball screw during operation of the injection molding machine;
• performing frequency analysis on a detected alternating current;
• and
• detecting an abnormality of the ball screw based on information related to a distribution of frequency components obtained by frequency analysis, and information related to a distribution of frequency components obtained by frequency analysis of an alternating current detected when the ball screw is normal comprising:
• calculating a statistical distance between a statistic of the distribution of frequency components obtained by frequency analysis of the alternating current detected by a current sensor and a statistic of the distribution of frequency components obtained by frequency analysis of the alternating current detected when the ball screw is normal, and detecting an abnormality of the ball screw based on the calculated statistical distance.