The Generation and Application of Random Numbers

In a roll assembly comprising a roll body and a ring made of hard material mounted securely on the barrel surface of said roll body by suitable tightening means, at least one of the lateral surfaces of the hard ring is formed in an outer-conical surface to which a clamp ring having a corresponding inner-conical surface is abutted thereon. The inside diameter of the clamp ring is substantially greater than the outside diameter of the roll body at the corresponding portion. The roll ring is pre-tightened by said suitable means together with the clamp ring which is pre-heated to a suitable temperature. The thermal contraction after cooling elicits principal tightening force.