Abstract: Stranded wire helical torsion spring is widely used in automatic weapons, there is still no
standard parametric modeling method. According to the geometrical forming principle of stranded
wire helical torsion spring, the functional relationship between the primary helix and the two helix is
analyzed, and the three - dimensional parametric modeling method of torsion spring is studied. In the
UG NX, using the dynamic expression modeling method, adopting “sweep”, “sketch” etc, a
parametric template for two - column three - strand helical torsion spring is established. Parametric
modeling is based on 81 and 56 7.62 mm rifle torsion spring parameters, and the feasibility of
parametric modeling is verified. In the process of stranded wire helical torsion spring modeling, the
standard naming is used to provide reference for all kinds of complex spring parametric modeling,
and promote the three - dimensional parameterization process of complex model.

Key words: stranded wire helical torsion spring, automatic weapons, parametric modeling, UG NX