Abstract: Taking a forging press as research object，relationship between the magnitude of interference and preload was determined by method of interference fit based on the ANSYS software. By analyzing the gap coefficient， contact state， contact pressure， tensile stress of dangerous tension rod and bending deformation of column， the effects of preload and eccentricity on the contact characteristics of combination frame were analyzed for the upsetting(condition 1)and drawing out(condition 2)in processes of forging and pressing. The results show that the condition of drawing out is more dangerous than that of the upsetting，and the gap coefficient should meet the following criteria:the contact area between the top rail and column greater than 05 and the gap coefficient β≤23. The results may provide a theory basis for structure design of forging press.

Key words: upsetting, drawing out, forging press, gap coefficient, contact characteristics