The present invention discloses a rolling-bulging forming hydraulic machine for tubular products, which includes a frame. The frame is provided with an upper rolling mechanism, a lower rolling mechanism, a fixed liquid bulging hydraulic cylinder and a movable liquid bulging hydraulic cylinder. The upper rolling mechanism and the lower rolling mechanism are arranged oppositely, and the upper rolling mechanism and the lower rolling mechanism are used to roll surfaces of a to-be-machined tubular product. The fixed liquid bulging hydraulic cylinder and the movable liquid bulging hydraulic cylinder are arranged oppositely, and the fixed liquid bulging hydraulic cylinder and the movable liquid bulging hydraulic cylinder are used to perform hydraulic bulging on the to-be-machined tubular product.

A large-size H-shaped steel product is produced by performing a rough rolling step including an edging rolling step of rolling and shaping a material to be rolled into a predetermined almost dog-bone shape, and a flat rolling step of performing rolling of a web part by rotating the material to be rolled after completion of the edging rolling step by 90° or 270°, upper and lower caliber rolls of at least one caliber of calibers configured to perform the flat rolling step include recessed parts configured to form a raised part at a middle of a web part of the material to be rolled, the recessed parts being provided at roll barrel length middle parts of the upper and lower caliber rolls.

The present invention discloses a rolling-bulging forming hydraulic machine for tubular products, which includes a frame. The frame is provided with an upper rolling mechanism, a lower rolling mechanism, a fixed liquid bulging hydraulic cylinder and a movable liquid bulging hydraulic cylinder. The upper rolling mechanism and the lower rolling mechanism are arranged oppositely, and the upper rolling mechanism and the lower rolling mechanism are used to roll surfaces of a to-be-machined tubular product. The fixed liquid bulging hydraulic cylinder and the movable liquid bulging hydraulic cylinder are arranged oppositely, and the fixed liquid bulging hydraulic cylinder and the movable liquid bulging hydraulic cylinder are used to perform hydraulic bulging on the to-be-machined tubular product.

A large-size H-shaped steel product is efficiently and stably produced by performing flat shaping and rolling of a large-size raw blank while improving a generation efficiency of flanges without bringing about problems such as elongation in a web height direction and deformation of a flange corresponding part. A rough rolling step includes an edging rolling step of rolling and shaping a material to be rolled into a predetermined almost dog-bone shape, and a flat rolling step of performing rolling of a web part by rotating the material to be rolled after completion of the edging rolling step by 90 or 270, upper and lower caliber rolls of at least one caliber of calibers configured to perform the flat rolling step include recessed parts configured to form a raised part at a middle of a web part of the material to be rolled, the recessed parts being provided at roll barrel length middle parts of the upper and lower caliber rolls, a width of the raised part formed in the flat rolling step is set to 25% or more and 50% or less of a web part inner size of the material to be rolled, and a thickness of the web part rolled in the flat rolling step is set to a predetermined thickness thicker than a web part thickness when the intermediate rolling step is started.

[Object] To suppress occurrence of shape defects in a material to be rolled and enable efficient and stable production of an H-shaped steel product with a flange width larger than a conventional flange width by creating deep splits on end surfaces of a material (e.g., slab) using projections with acute-angle tip shapes, and sequentially bending formed flange portions. [Solution] Provided is a method for producing H-shaped steel, the method including: a rough rolling step; an intermediate rolling step; and a finish rolling step. In a rolling mill that performs the rough rolling step, a plurality of calibers to shape a material to be rolled are engraved, the number of the plurality of calibers being four or more. Shaping of one or a plurality of passes is performed on the material to be rolled in the plurality of calibers. In a first caliber and a second caliber among the plurality of calibers, projections to create splits vertically with respect to a width direction of the material to be rolled are formed. In a second caliber and subsequent calibers among the plurality of calibers, reduction is performed in a state where end surfaces of the material to be rolled are in contact with caliber peripheral surfaces in shaping of at least one pass. In a third caliber and subsequent calibers among the plurality of calibers, a step of sequentially bending divided parts formed by the splits is performed.

[Object] To suppress occurrence of shape defects in a material to be rolled and enable efficient and stable production of an H-shaped steel product with a flange width larger than a conventional flange width by creating deep splits on end surfaces of a material (e.g., slab) using projections with acute-angle tip shapes, and sequentially bending formed flange portions.

[Solution] Provided is a method for producing H-shaped steel, the method including: a rough rolling step; an intermediate rolling step; and a finish rolling step. In a rolling mill that performs the rough rolling step, a plurality of calibers to shape a material to be rolled are engraved, the number of the plurality of calibers being four or more. Shaping of one or a plurality of passes is performed on the material to be rolled in the plurality of calibers. In a first caliber and a second caliber among the plurality of calibers, projections to create splits vertically with respect to a width direction of the material to be rolled are formed. In a second caliber and subsequent calibers among the plurality of calibers, reduction is performed in a state where end surfaces of the material to be rolled are in contact with caliber peripheral surfaces in shaping of at least one pass. In a third caliber and subsequent calibers among the plurality of calibers, a step of sequentially bending divided parts formed by the splits is performed.