Abstract: As to the complexity in structure and shape of work house and roll system in cross wedge mills, the new method is developed to calculate the rigidity of cross wedge mill, which is called the coupling method of 3-D elastic contact boundary element method with multi-bodies and finite element method. The new method can update the existing deforming separation calculating theory and corresponding methods of material mechanics, elastic me-chanics and finite element method. It gets over the disadvantage of not inclusion of roll system in the traditional calculation of rigidity. It has stronger synthesis and fewer hypotheses in contact-type calculating model. This new method owns high calculation rate, high calculation accuracy, etc.

Key words: Boundary element method, Finite element method, Mill rigidity