Design and manufacturing of a welding-jig for tailor-made bicycle frames

Abstract: The handling behavior is a complex system influenced by many parameters. While many components can improve the comfort or performances of a mountain bike, the frame stays the main component that will define its handling. Indeed, as explained in this report literature review, each geometrical parameters of the frame influences greatly the bicycle handling. Every rider being different in anatomy or style of riding, it is necessary to adapt the frame to each rider to reach the best level of performances. The core of the tailor-made manufacturing of a bicycle is the positioning and holding of the tubes relatively to each other, a process that is carried via the use of a customizable welding-jig. This report analyses the current welding-jigs available on the market and describes in details the design and manufacturing of a unique welding-jig for tailor-made bicycle frame for Nicolai GmBH, a German company specialized in the manufacturing of high end bicycle frames. In addition, this report introduces the reader to an internet form listing all the combination of the bicycle industry’s standards used by Nicolai GmBH. This internet form has for purpose to facilitate the understanding of the customer willing to buy a tailor-made bicycle frame. The welding-jig has been designed on the Computer Aided Design software SolidWorks and is made of an assembly of Bosch Rexroth aluminum extruded profiles and their standard accessories and parts machined at Nicolai GmBH. Besides ensuring the positioning and holding of the different elements of a bicycle frame, it has the particularity to: - Display every geometrical parameter of a bicycle frame. - Be able to build a broad range of bicycle frame sizes. - Give an easy access to all the parts of the frame to the welder. - Reduce the number of aligning process in the manufacturing of a bicycle frame. - Be easily movable. This report presents also the calibration process of the welding jig and the description of its setting process. The welding-jig presented in this report has been tested successfully at Nicolai GmBH for the manufacturing of a hardtail bicycle frame. It is also highly appreciated by the technicians and engineer using it.