Abstract: How to keep and fasten reliably the adjusted posture is always a key problem in large components assembly such as airplane. Based on the phase-change principle of low-melting-point alloy, a new posture following fixture method of large components and a posture following fixture are presented, and it is proved feasible and reliable by a series of experiments and calculations. The method is described as follows: heat and melt the low-melting-point alloy in the cylindrical metal, insert the mandrel rigidly jointed with the large component into the melted alloy, and cool the metal to keep and fasten reliably the mandrel without posture change, and lock the inner core rigidly connected with the cylindrical metal, reheat and remelt the low-melting- point alloy again to release the mandrel and to resume the adjustable posture of the large component.

Key words: Fixation, Large components, Low-melting-point alloy, Phase change, Constant rotational stiffness, Gimbaled device, Hooke hinge, Static balancing instrument, Unbalance moment, Cross-spring pivot