Hole-shaped structure of phi-65-mm bar and rolling method thereof

The invention relates to a hole-shaped structure of a phi-65-mm bar. An eighth-sortie hole shape adopts a multi-radius elliptical hole structure; the upper portion of the eighth-sortie hole shape comprises first circular-arc parts, second circular-arc parts engaged with the first circular-arc parts and transition groove opening circular corners transiting to groove opening planes; the lower portion of the eighth-sortie hole shape is symmetrical to the first circular-arc parts and the second circular-arc parts and is engaged to the groove opening planes by the second circular-arc parts. A ninth-sortie hole shape adopts a circular hole structure with a linear side wall; the upper portion of the ninth-sortie hole shape comprises third circular-arc parts which are connected to groove opening planes through tangent lines, and the lower portion and the upper portion of the ninth-sortie hole shape are symmetrical. The invention further relates to a rolling method of the hole-shaped structure of the phi-65-mm bar. Th