Gapping Factor Analysis of Heavy Hydraulic Press with Whole Pre-Tightening Assembled Frame

Whole pre-tightening assembled frame with multi tension bolts, the main form of heavy hydraulic press, will gap at the junctions of upper beam and columns when it is subjected to allowable loads, which has great influence on stability of assembled frame and processing quality of forgeable piece. A model of assembled frame with 10 tension bolts was built to research the effect of residual pretension coefficient, relative stiffness coefficient and distribution of tension bolts on gapping by means of numerical simulation. Relative gapping coefficient and relative potential gapping coefficient were introduced to measure the extent of gapping. Our studies indicated that residual pretension coefficient was the most important influence factor, while distribution of tension bolts had little influence on extent of gap.