Hydrojoining

Manufacturing of complex tube-workpieces often requires medium-based forming processes. Because of the inaccessibility to the inside of the parts, joining of attached parts is difficult. Additional part handling and process steps are necessary. A loss of the high accuracy of hydroformed parts is disadvantageous especially by shape distortion during thermal joining. One solution is the integration of the joining operation into the hydroforming-process. A new integration method is a combination of hydroforming and spot-joining. Spot joining means a version of joining by forming like clinching or self-pierce riveting or fluid molding of functional elements, e.g. with inside or outside thread. The high pressure fluid takes over the task of the die during hydrojoining. This integrated die-less procedure also increases the range of possibilities which are not available with standard techniques. The potential and limits of these new hydrojoining-methods are compared with alternative procedures.