Material-specific predicting of the optimal joining parameters for the screw blind rivet joining process

Abstract

Abstract The screw-blind riveting combines direct screwing with the blind riveting. The novel joining element can be integrated into every injection-molded component like a standard screw boss without significantly increasing the processing time. The screw-blind-rivet (SBR) consists of a screw boss connected to a substrate by a thin sleeve. The joining process of screw-blind-riveting can be divided into two phases. The first is the screw-in phase. The screw is secured into the SBR. The second phase is the forming phase. Further turning of the screw will cause the sleeve to buckle out and form an undercut. To qualify the connection element for industrial use, in addition to the strengths of the design, suitable connection parameters are required for the user. The independent parameters of the joining process are the contact pressure of the screw and the screwing-in speed. The rate is reduced to avoid damage and ensure a proper alignment. The speed after the headrest is an additional influencing parameter. The most influencing parameter for the undercut is the rotation angle after the initial screw placement as it affects the shape of the undercut. The larger the undercut is, the more stable the rivet. However, the larger the undercut is, the more deformations and material damage occur. Thus, the optimal angle for the forming depends on the material of the rivet. Consequently, the deformation angle must be selected depending on the material properties. For this, various materials were tested. The results show a well predictability of the optimum joining parameters by using the elongation at yield stress of the used material.