An integrated approach to the high-speed machining of moulds and dies involving both a knowledge-based system and a chatter detection and control system

Abstract

Over the past decade, high-speed machining (HSM) has provided a step change in productivity for the manufacture of moulds and dies, particularly those made from tool steels in the fully hardened state. Advantages include reduced machining times and costs and favourable workpiece surface integrity. The knowledge and expertise that have been generated in academia and industry are widespread and important for the e¤cient utilization of HSM. Following a survey of relevant publications, the present paper details the development of an integrated system for the HSM of moulds and dies. This included the design and implementation of a knowledge-based system (KBS) and a chatter detection and control system. The main modules of the KBS related to machine tools, cutting tools and machinability data, toolholders, cutter path strategies and troubleshooting, together with a database management centre. Ranking techniques were employed with combined weighing factors, together with tool rationalization and reduction strategies, fuzzy logic and machinability data optimization. The chatter detection and control system utilized a microphone to detect chatter and employed online spindle speed and feed rate modi®cation strategies for its suppression. The system was capable of being interfaced with the KBS in order to transfer and store local knowledge unique to a particular toolmaker's operations.

Chatter prevention and improved finish of workpiece for a milling process

“…Chiou and Liang proposed a dynamic model of the cutting acoustic emission signal to predict the phenomenon of chatter vibration in the neighbourhood of the chatter frequency of the tool [15]. Based on the concept of sound monitoring [3,11,[15][16][17], chatter prevention by feedback of the acoustic cutting signal is proposed and verified by realistic cutting experiments in the present work. The real-time feedback acoustic signal, having been filtered to remove the components caused by power supply frequency, machine motion, and highfrequency noise, is converted into a quantitative signal index, which is named the acoustic chatter signal index (ACSI), and a spindle speed tuning command is then determined by the controller, synthesized in advance, according to the innovative ACSI level.…”