On-line condition monitoring of power press tooling using ultrasonics.
The principal objective of the research programme was to
develop a technique for monitoring the condition of
power-press cutting tools using ultrasonics. The principle of
the technique was based upon the reflection of Surface
Acoustic Waves (SAWs) from the tooling's cutting edges, and
the main aim of the research was to establish the
relationship between reflected SAW amplitude and tool edge
condition. Three approaches were used to establish the
relationship, namely on-line experiments, off-line bench-top
experiments, and mathematical modelling. The modelling work
involved using Transmission Line Modelling.
Three types of wear were observed on the punch:
i. The formation of a wear radius on the cutting edge of
ii. The beating back of the bottom face of the punch
adjacent to the cutting edge.
iii. The formation of an abraded region on the flank of the
punch adjacent to the cutting edge.
The research has shown that it is possible to monitor the
radius that forms on the cutting edge of the punch using the
amplitude of SAW pulses reflected from the edge. Also the
work has indicated that the rate of radius formation is a
function of the clearance between the punch and the die.
However, the effects of the change in the cutting edge's
condition on the propagation delay of the SAWs, which was
also investigated, was not found to be significant.
Whilst in principle it should be possible to automatically
monitor the condition and predict the wearing out of
press-tools, the development of a working tool-moni toring
system capable of monitoring the complete cutting edge of a
press-tool is presently being hindered due to the lack of a