A rolling mill includes three or more rolling rolls aligned along a circumferential direction and arranged so each rotary shaft is skewed with respect to a pass line of a material to be rolled, wherein the material to be rolled made of a pipe or bar material passes between the rolling rolls while being rotated to undergo diameter reducing rolling. At least one rolling roll selected from the three or more rolling rolls is smaller in roll diameter than at least one other rolling roll. When at least one rolling roll having a relatively maximum roll diameter defined as a maximum diameter rolling roll and at least one rolling roll smaller in roll diameter than the maximum is defined as a small diameter rolling roll, the small diameter rolling roll has a roll diameter equal to or less than 90% of the roll diameter of the maximum diameter rolling roll.

A method for deep roll peening a workpiece includes deep roll peening a workpiece by moving the workpiece along a feed path through multiple groups of opposed rollers that are arranged in series. Each group of opposed rollers includes a rim that defines a workpiece engagement surface that exerts a deep roll peening force on the workpiece. A deep roll peening system includes multiple groups of opposed rollers. Each of the opposed rollers is rotatably mounted and has a rim that defines a workpiece engagement surface. The workpiece engagement surfaces are spaced apart from each other by a gap. The groups are arranged in series such that the gaps define a feed path for receiving a workpiece into serial contact with the workpiece engagement surfaces.

A method for deep roll peening a workpiece includes deep roll peening a workpiece by moving the workpiece along a feed path through multiple groups of opposed rollers that are arranged in series. Each group of opposed rollers includes a rim that defines a workpiece engagement surface that exerts a deep roll peening force on the workpiece. A deep roll peening system includes multiple groups of opposed rollers. Each of the opposed rollers is rotatably mounted and has a rim that defines a workpiece engagement surface. The workpiece engagement surfaces are spaced apart from each other by a gap. The groups are arranged in series such that the gaps define a feed path for receiving a workpiece into serial contact with the workpiece engagement surfaces.

A method for deep roll peening a workpiece includes deep roll peening a workpiece by moving the workpiece along a feed path through multiple groups of opposed rollers that are arranged in series. Each group of opposed rollers includes a rim that defines a workpiece engagement surface that exerts a deep roll peening force on the workpiece. A deep roll peening system includes multiple groups of opposed rollers. Each of the opposed rollers is rotatably mounted and has a rim that defines a workpiece engagement surface. The workpiece engagement surfaces are spaced apart from each other by a gap. The groups are arranged in series such that the gaps define a feed path for receiving a workpiece into serial contact with the workpiece engagement surfaces.

A milling apparatus includes a plurality of milling roller units each including one milling roller that is made contact with, by pressing, one surface of one of a plurality of differently angled plate parts of an elongated metal milling material and another milling roller that is made contact with another surface of the plate part by pressing. At least one of the milling roller units mills a plate part different from a plate part milled by any other milling roller unit. A plurality of the milling roller units configured to mill an identical plate part are installed in a longitudinal direction of the plate part. The one milling roller and the other milling roller of at least one of the milling roller units are movable in axial directions thereof.

A milling apparatus includes a plurality of milling roller units each including one milling roller that is made contact with, by pressing, one surface of one of a plurality of differently angled plate parts of an elongated metal milling material and another milling roller that is made contact with another surface of the plate part by pressing. At least one of the milling roller units mills a plate part different from a plate part milled by any other milling roller unit. A plurality of the milling roller units configured to mill an identical plate part are installed in a longitudinal direction of the plate part. The one milling roller and the other milling roller of at least one of the milling roller units are movable in axial directions thereof.

A method for deep roll peening a workpiece includes deep roll peening a workpiece by moving the workpiece along a feed path through multiple groups of opposed rollers that are arranged in series. Each group of opposed rollers includes a rim that defines a workpiece engagement surface that exerts a deep roll peening force on the workpiece. A deep roll peening system includes multiple groups of opposed rollers. Each of the opposed rollers is rotatably mounted and has a rim that defines a workpiece engagement surface. The workpiece engagement surfaces are spaced apart from each other by a gap. The groups are arranged in series such that the gaps define a feed path for receiving a workpiece into serial contact with the workpiece engagement surfaces.

A method for deep roll peening a workpiece includes deep roll peening a workpiece by moving the workpiece along a feed path through multiple groups of opposed rollers that are arranged in series. Each group of opposed rollers includes a rim that defines a workpiece engagement surface that exerts a deep roll peening force on the workpiece. A deep roll peening system includes multiple groups of opposed rollers. Each of the opposed rollers is rotatably mounted and has a rim that defines a workpiece engagement surface. The workpiece engagement surfaces are spaced apart from each other by a gap. The groups are arranged in series such that the gaps define a feed path for receiving a workpiece into serial contact with the workpiece engagement surfaces.

A method for deep roll peening a workpiece includes deep roll peening a workpiece by moving the workpiece along a feed path through multiple groups of opposed rollers that are arranged in series. Each group of opposed rollers includes a rim that defines a workpiece engagement surface that exerts a deep roll peening force on the workpiece. A deep roll peening system includes multiple groups of opposed rollers. Each of the opposed rollers is rotatably mounted and has a rim that defines a workpiece engagement surface. The workpiece engagement surfaces are spaced apart from each other by a gap. The groups are arranged in series such that the gaps define a feed path for receiving a workpiece into serial contact with the workpiece engagement surfaces.

A method for deep roll peening a workpiece includes deep roll peening a workpiece by moving the workpiece along a feed path through multiple groups of opposed rollers that are arranged in series. Each group of opposed rollers includes a rim that defines a workpiece engagement surface that exerts a deep roll peening force on the workpiece. A deep roll peening system includes multiple groups of opposed rollers. Each of the opposed rollers is rotatably mounted and has a rim that defines a workpiece engagement surface. The workpiece engagement surfaces are spaced apart from each other by a gap. The groups are arranged in series such that the gaps define a feed path for receiving a workpiece into serial contact with the workpiece engagement surfaces.