Development and implementation of a dynamic force measurement system for automatic tool changer system and drawbar mechanism in machining center

Automatic tool changer system (ATCS) and drawbar mechanism (DM) are two of key basic parts for realizing the automatic tool-changing cycle in machining centers. The dynamic force in a tool-changing cycle plays an essential role in condition monitoring, fault diagnosis, and failure warning for the ATCS and DM. However, existing force detection systems have limitations in practical application. In this paper, a novel dynamic force measurement system (DFMS) is developed, which is based on a force sensing element installed on the BT40 tool holder and operating through a wireless network. The force sensing element is used to convert the dynamic force into the electrical signal. Digital measurements are collected from the 24-bit sigma-delta analog-to-digital converter with a programmable gain array, which then are transmitted to the upper computer software via a wireless transceiver. Besides, a Teager energy operator based dual-threshold two sentences endpoint detection method is proposed to recognize the temporal onset and offset of each force event in the dynamic force recording. Experimental results show that the DFMS is reliable and suitable to measure the dynamic force in automatic tool-changing cycles.