Analytical modelling of the automated dispensing of adhesive materials

Abstract

The integrity of joints is a critical issue in structural bonding and the shape of adhesive beads needs to be consistent. The right amount of adhesive must be dispensed and to ensure this, the dispensing process must be automated. To have a fully automated dispensing cell, the use of a knowledge-based expert system for set-up and diagnosis is appropriate. To achieve this, the modelling of dispensing flow of adhesive material is essential to ensure that the correct sized bead is dispensed at a variety of robot speeds. For a given adhesive, it is often necessary to perform many ad hoc adjustments and tests to produce optimal adhesive beads at different operational and environmental conditions. To avoid this, the rheological behaviour of the adhesives is analysed, to find a constitutive equation for representing an adhesive model which best describes the way that different types of adhesives flow under a variety of conditions. Modelling the material properties provides an initial approximation of the flow rate for dispensing the adhesive. The automated dispensing cell can then adapt to the operational conditions where the model also provides for its initial set-up and diagnosis. This modelling method can also be applied to similar adhesives with known rheological data and nozzle flow rate.