The　assembly　accuracy　of　the　guide　rail　is　closely　related　to　the　distribution　state　of　the　preload　force　of　the　bolt　group.　Bolts　have　relaxation　characteristics　during　service,　and　the　distribution　of　preload　force　gradually　changes　over　time,　which　in　turn　affects　the　assembly　accuracy　of　the　guide　rail.　This　article　focuses　on　the　time-varying　characteristics　of　the　distribution　of　preload　force　in　bolt　groups　under　different　factors.　Firstly,　the　relationship　between　the　deformation　of　guide　rail　assembly　and　the　distribution　of　preload　force　was　analyzed.　Secondly,　based　on　the　combined　time　hardening　model,　the　general　law　of　the　dispersion　of　bolt　pre-　tightening　force　evolution　over　time　was　analyzed.　Finally,　the　time-varying　law　of　the　preload　force　dispersion　of　the　bolt　group　was　analyzed　under　different　pitches,　joint　surface　friction　coefficients,　and　preload　force　loading　times.　The　results　show　that　the　dispersion　of　surface　node　deformation　on　the　guide　rail　is　positively　correlated　with　the　dispersion　of　preload　force;　The　dispersion　of　preload　force　gradually　decreases　with　time,　and　the　downward　trend　gradually　becomes　gentle;　Secondly,　as　the　pitch　and　friction　coefficient　increase,　the　initial　preload　dispersion　gradually　increases,　and　the　corresponding　dispersion　also　gradually　increases　at　the　same　creep　moment.　However,　the　percentage　of　dispersion　decay　gradually　decreases　within　the　same　time　period;　The　number　of　times　the　bolt　preload　force　is　loaded　follows　the　opposite　pattern.　©　2024　SPIE.