Alignment through bolted Connections: a Comparative Investigation Among different Geometric Specifications

摘要

One commonly overlooked design rule advises against relying on bolts to ensure alignment between parts. Bolted connections often require a significant nominal size difference between screws and holes to avoid interference during assembly. Using the boundary condition design criterion, it is possible to define dimensional and location tolerances for this purpose, but it typically results in clearance being expected, thus accurate alignment cannot be assured. Despite this, many industrial practices still utilize bolted connections (or more broadly, shaft-hole connections) to align different parts. While automated assembly lines might resolve alignment issues through robotic arms, such designs lack robustness, especially when viewed from a design-for-maintenance perspective. During service or maintenance, correctly reassembling bolted parts can become a challenging task. This paper aims to address these issues by applying tolerance stack-up analysis to various possible geometric specifications. The study will explore the impact of a dedicated alignment feature and analyze the influence of material conditions on the geometric specification quantifying rejection rates. To accomplish this, a straightforward assembly involving two parts bolted together will be examined. The study will assess the effects of different specifications, encompassing both functional specification (representing assembly conditions) and non-functional specification (based on fiducial features).