Abstract : Our work characterizes the argumentative process by which designers having different expertise interact in order to elaborate a solution that satisfies each of the designer's constraints. In a first empirical study, researchers in linguistics, cognitive science and mechanical engineering jointly carry out a descriptive analysis. This analysis allows us to define a typology of collaborative interactions in design. We identify a set of interactional mechanisms showing, for example the predominance of certain interactions or the similarity of designers' profiles. We then build argument graphs that help us to identify patterns of argumentative interactions already known in the literature. The analysis of our graphs also shows the importance of the analogy criterion in design activity. During our second empirical study, we create and implement a tool to assist designers in collectively constructing analogies. However, the tool is not integrated into our designers' practices and thus we reflect upon the necessary conditions for practitioners' successful appropriation of new tools.