Design of an Auxiliary Manipulator for Threaded Hole Machining in Narrow Spaces

In mechanical manufacturing and daily maintenance, it is often necessary to process threaded holes on large components in narrow spaces such as pipes or corners. Traditional machine tools cannot operate due to spatial constraints, while handheld devices struggle to guarantee accuracy. This study designs an auxiliary machining system based on robotic arm technology to address the challenge of threaded hole machining in confined spaces. The manipulator integrates a magnetic base, a feed mechanism, angle and height adjustment devices, a laser positioning system, and a drilling power unit. The rotary cutting motion is achieved by a DC motor driving a gear reducer; the feed motion is accomplished via a manually operated rack and pinion mechanism; and positioning is realized by two linear infrared lasers arranged at a 90° cross angle. This paper focuses on presenting the overall scheme, key mechanism designs, and working principles of the manipulator. It also includes the design and calculation of the rack and pinion transmission for the feed mechanism. Finite element analysis was performed on critical load-bearing components (e.g., the handle) using SolidWorks software to verify structural safety. The design features a small size, high flexibility, and convenient operation, making it suitable for various narrow space scenarios and capable of significantly improving machining efficiency and precision.