Cluster type multistage rolling mill

A cluster type multistage rolling mill comprising a top inner housing for containing a group of rolls arranged above a pass line;

• a bottom inner housing for containing a group of rolls arranged below the pass line;
• and an operating side and a driving side outer housings for containing said top and said bottom inner housings, which comprises:
• a top side supporting means for supporting the upper side of said top inner housing to said outer housings in the operating side and the driving side each at two points in the front side and in the back side with respect to a pass direction, said top side supporting means being arranged in the upper side of said top inner housing and between said operating side and said driving side outer housings;
• and
• a bottom side supporting means for supporting the lower side of said bottom inner housing to said outer housings in the operating side and the driving side each at one point in the middle with respect to the pass direction, said bottom side supporting means being arranged in the lower side of said bottom inner housing and between said operating side and said sdriving side outer housings, wherein
• when a vertical rigidity ratio between said top and said bottom inner housings is defined as a rigidity of said top inner housing/a rigidity of said bottom inner housing, the housing proportion is formed so that the vertical rigidity ratio may become a value within a range of 1.02 to 1.18.

A cluster type multistage rolling mill comprising a top inner housing for containing a group of rolls arranged above a pass line;

• a bottom inner housing for containing a group of rolls arranged below the pass line;
• and an operating side and a driving side outer housings for containing said top and said bottom inner housings, which comprises:
• a top side supporting means for supporting the upper side of said top inner housing to said outer housings in the operating side and the driving side each at two points in the front side and in the back side with respect to a pass direction, said top side supporting means being arranged in the upper side of said top inner housing and between said operating side and said driving side outer housings;
• and
• a bottom side supporting means for supporting the lower side of said bottom inner housing to said outer housings in the operating side and the driving side each at one point in the middle with respect to the pass direction, said bottom side supporting means being arranged in the lower side of said bottom inner housing and between said operating side and said driving side outer housings, wherein
• a height of said bottom inner housing is higher than a height of said top inner housing.

A cluster type multistage rolling mill comprising a top inner housing for containing a group of rolls arranged above a pass line;

• a bottom inner housing for containing a group of rolls arranged below the pass line;
• and an operating side and a driving side outer housings for containing said top and said bottom inner housings, which comprises:
• a top side supporting means for supporting the upper side of said top inner housing to said outer housings in the operating side and the driving side each at two points in the front side and in the back side with respect to a pass direction, said top side supporting means being arranged in the upper side of said top inner housing and between said operating side and said driving side outer housings;
• and
• a bottom side supporting means for supporting the lower side of said bottom inner housing to said outer housings in the operating side and the driving side each at one point in the middle with respect to the pass direction, said bottom side supporting means being arranged in the lower side of said bottom inner housing and between said operating side and said driving side outer housings, wherein
• a width in the pass direction of said bottom inner housing is wider than a width in the pass direction of said top inner housing.