Riveting Squeezing Force Estimation: A Revised Algebraic Model

The riveting process is widely used by the aeronautical industry, mainly in joining sheet metal aluminum alloys. In this process, squeezing force is one of the main setup parameters used to control the quality of the joining process, mainly on automated riveting machines. That squeezing force can be estimated or checked based on the rivet material parameters (hardening constants) and on the driven rivet head dimensions before and after the force application. The equation, commonly used in literature, tends to underestimate, by a relatively small amount, the squeezing force at high squeezing ratios and slightly overestimate at median ratios. This is due to the influence of the following two factors not considered in the original equation: riveted grip thickness and friction among rivet, sheet, and punch tools. In this work, a revised algebraic model is proposed. The new model is still simple and easily adaptable to a spreadsheet or to a computer code like MATLAB®, R®, Scilab®, or Python®. Using the proposed model, the calculated squeeze force values tend to be more accurate at the squeeze ratios normally used by the aeronautical industry.