Development of extension tool for high dynamic tightening : Degree project in Mechanical Engineering, specialisation Machine Design

Abstract: Atlas Copco Industrial Technique AB is a global supplier of systems, software, services, and tools for the global assembly industry with keywords such as ergonomics, productivity, and traceability central to Atlas Copco’s products. The objective of the thesis was to construct a prototype tool based on the result of a previous course held at Luleå University of technology. The course provided the development of a conceptual tool that utilized a chain driveline to transmit high dynamic torque to a bolt and an experimental setup with torque measurements. The scope of the thesis, as for the course, was to design a tool able to tighten joints up to 150Nm utilizing a pulsating tightening technique with the goal of no increase of defined dimension and vibrations lower than1m/s2. The thesis was initiated with a state-of-art benchmark where potential drivelines and competing solutions were acquired and were followed by the establishment of the framework for the prototype, a decided driveline, dimensioning of the components, the modeling and order of the prototype and a stiffness study. When the prototype was assembled and three competing solutions were obtained, vibrational, torsional and stiffness experiments were conducted.The experimental measurements concluded that the tool could tighten the sought 150Nm joints but with a declared vibrational value of ahd = 8.6m/s2. The extension tool also increased the vital centre-to-side distance by 5.5mm compared to the STR61-150 tool. The thesis examined the association between chain tension and torque transmission but could not determine this relationship. However, the experiment conducted suggests that an increasing chain tension would overall increase the magnitude of the pulse.