Impact of Anchor Bolts Creep Relaxation on Geometric Accuracy Decline of Large Computer Numerical Control Machine Tools[J]. 2015, 49(9): 14-17+140.
DOI:
Impact of Anchor Bolts Creep Relaxation on Geometric Accuracy Decline of Large Computer Numerical Control Machine Tools[J]. 2015, 49(9): 14-17+140.DOI: 10.7652/xjtuxb201509003.
Impact of Anchor Bolts Creep Relaxation on Geometric Accuracy Decline of Large Computer Numerical Control Machine Tools
Aiming at anchor bolt creep relaxation of large CNC machine tools
a calculation model for preload and creep force of the distributed bolts is established
where both bolts creep at room temperature and elastic interaction among bolt-hole units are taken into consideration. A simulation for anchor bolt sequential preload and creep is also conducted and utilized to reveal the influence of bolt creep relaxation on machine geometric accuracy decline quantitatively. Furthermore
three creep parameters of the 8.8 level T-type anchor bolt are estimated via the drawing experiments under 20 ℃ ambient temperature. After 9 000 hours creep simulation
the anchor bolt preload relaxation reaches 14.8%
and the relative accuracy declines of straightness and parallelism of bed linear guide mounting surfaces get 4.3 μm and 2.8 μm
respectively. The developed model can be used for the fundamental parts bolt preload optimization and the geometric accuracy retention capability enhancement of large CNC machine tools.
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