Design of clinched joints on the basis of binding mechanisms

Abstract

The work carried out is based on the thesis properties of clinched joints are determined by the proportions of binding mechanisms form-closure, force-closure and material-closure. To describe the acting binding mechanisms and thus to derive the joint properties, detailed knowledge of the local effect of the individual binding mechanisms is necessary to ensure their targeted adjustment by the joining process. The targeted setting of different proportions of the binding mechanisms is achieved firstly via tool geometry and secondly via surface condition of the joined parts. An introduced form-closure component can be quantified by metallographic cross section with subsequent measurement of the quality-determining parameters such as undercut, penetration depth and neck thickness. To qualify the force-closure component, a torsional load can be applied mechanically at rotationally symmetrical clinch joints. This also allows the influence of different surface conditions on the tribological system to be quantified. Measurement of electrical resistance can reveal the binding mechanisms of force- and material-closure. These investigations are carried out on an aluminum joining part combination of the same type. As a result of these investigations, the clinched joints can be designed according to the load occurring in the later life cycle in the form of an optimum and compromise variant with regard to minimum loads to be transmitted mechanically, electrically with regard to low resistance or manufacturing with minimum energy input.

Approach to Determine the Characteristic Dimensions of Clinched Joints by Industrial X-ray Computed Tomography

“…The mechanisms at this point can be diverse. However, it can be assumed that the tin layer prevents the material closure described in [11]. Only the median value of the MATLAB-based CT and the median values of the micrograph analyses are close to each other at approx.…”

“…The poor contrast between sheet and interface prevents their use as starting points for measuring the characteristic dimensions. Furthermore, at some points, partial metallic bonding occurs [11]. Consequently, the interface is not visible in the CT scan making the measurement of the undercut or the neck thickness impossible.…”