Innovative Design and Performance Optimization Research on Double-End Stud Assembly Wrenches

As a type of threaded fastener, double-end studs are widely used in various mechanical equipment. Due to their special structure—threaded on both ends with a smooth shank in the middle—they lack standard driving features such as hexagonal heads, internal hexagons, or slotted or cross recesses, which are common in other threaded fasteners. This makes it difficult for conventional tools to perform convenient, efficient, and high-quality assembly operations. This paper systematically introduces the design and optimization process of a novel wrench specifically for double-end stud assembly. Through iterative optimization, an innovative dedicated wrench structure was ultimately developed. Experimental data demonstrate that this wrench significantly improves assembly efficiency, reducing the average assembly time per stud from 46.2 seconds with traditional methods to 22.7 seconds—an efficiency increase of 50.9%. Moreover, the wrench greatly enhances assembly quality, lowering the thread damage rate from 15.4% to 1.1%. The tool is compatible with double-end studs in various specifications ranging from M12 to M24, offering broad applicability.