A device to process a blank (3) that includes at least one outer shaping tool (8) that may be radially positioned or radially displaced. An inner shaping tool (9) is mounted co-axially to the main machine axis (x) of the main spindle (1.1). The inner shaping tool (9) may be axially displaced and/or axially positioned with respect to the axial position of the outer shaping tools (8).

A device to process a blank (3) that includes at least one outer shaping tool (8) that may be radially positioned or radially displaced. An inner shaping tool (9) is mounted co-axially to the main machine axis (x) of the main spindle (1.1). The inner shaping tool (9) may be axially displaced and/or axially positioned with respect to the axial position of the outer shaping tools (8).

A rolling plant (R) for rolling tubes having a multi-stand rolling mill (5) with two or more rolls, in order to implement a controlled speed mandrel rolling process, comprises a hooking and releasing device (61) which is arranged in the inlet area of the rolling mill (5) to cooperate with the rear tang of the mandrel (31) and a hooking and releasing device (71) which is arranged in the outlet area of the rolling mill (5) to cooperate with the front tang of the mandrel (31) in coordinated manner with the first hooking and releasing device (61).

A rolling plant (R) for rolling tubes having a multi-stand rolling mill (5) with two or more rolls, in order to implement a controlled speed mandrel rolling process, comprises a hooking and releasing device (61) which is arranged in the inlet area of the rolling mill (5) to cooperate with the rear tang of the mandrel (31) and a hooking and releasing device (71) which is arranged in the outlet area of the rolling mill (5) to cooperate with the front tang of the mandrel (31) in coordinated manner with the first hooking and releasing device (61).

A manufacturing method of a seamless metal pipe includes: preparing a plurality of mandrel bars in which lengths of work portions which come into contact with a hollow shell during elongating are different from one another; selecting a mandrel bar including a work portion having a length corresponding to the number of stands used in thickness reduction, among the plurality of mandrel bars; inserting the mandrel bar selected in the selecting into the hollow shell; and performing the elongating on the hollow shell into which the mandrel bar is inserted. Moreover, in the elongating, outer diameter reduction is performed by one of a preceding-stage stand group and a succeeding-stage stand group and the thickness reduction is performed by the other of the preceding-stage stand group and the succeeding-stage stand group, or the thickness reduction is performed by both of the preceding-stage stand group and the succeeding-stage stand group.

A manufacturing method of a seamless metal pipe includes: preparing a plurality of mandrel bars in which lengths of work portions which come into contact with a hollow shell during elongating are different from one another; selecting a mandrel bar including a work portion having a length corresponding to the number of stands used in thickness reduction, among the plurality of mandrel bars; inserting the mandrel bar selected in the selecting into the hollow shell; and performing the elongating on the hollow shell into which the mandrel bar is inserted. Moreover, in the elongating, outer diameter reduction is performed by one of a preceding-stage stand group and a succeeding-stage stand group and the thickness reduction is performed by the other of the preceding-stage stand group and the succeeding-stage stand group, or the thickness reduction is performed by both of the preceding-stage stand group and the succeeding-stage stand group.

A method for producing a plug includes: a step of preparing a plug base metal having a concave portion along a circumferential direction in an outer peripheral surface; and an arc spraying step of spraying a spraying wire rod material onto the outer peripheral surface of the plug base metal by arc spraying to form films containing Fe and Fe oxides on the outer peripheral surface of the plug base metal. The arc spraying step includes: a separating step of separating the outer peripheral surface of the plug base metal into a plurality of regions along an axial direction; and a step of performing arc spraying separately in each of the regions. In the separating step, a boundary between the regions is set at the concave portion. In this way, peeling of films at a connecting portion is prevented, and the lifetime of the plug can be increased.

A method for producing workpieces wherein a substantially rotationally symmetrical workpiece (4, 9, 33), which has a workpiece axis (22), is tentered concentrically relative to an inner mandrel (3, 16) provided inside the workpiece (4, 9, 33), and is reshaped by a process of flow forming by radially applying external reshaping rollers (7). The wall thickness of the workpiece (4) is also reduced in at least some regions. The inner diameter (18, 41) of the workpiece (33) is enlarged by applying inner reshaping rollers (11) of an inner reshaping unit. The inner reshaping rollers (11) are arranged such that the roller axes of rotation and the enveloping cone (20) all intersect at one point on the workpiece axis (22).

A method for producing workpieces wherein a substantially rotationally symmetrical workpiece (4, 9, 33), which has a workpiece axis (22), is tentered concentrically relative to an inner mandrel (3, 16) provided inside the workpiece (4, 9, 33), and is reshaped by a process of flow forming by radially applying external reshaping rollers (7). The wall thickness of the workpiece (4) is also reduced in at least some regions. The inner diameter (18, 41) of the workpiece (33) is enlarged by applying inner reshaping rollers (11) of an inner reshaping unit. The inner reshaping rollers (11) are arranged such that the roller axes of rotation and the enveloping cone (20) all intersect at one point on the workpiece axis (22).

The invention relates to a method for producing seamless steel tubes in a rolling mill train with one or more consecutively positioned longitudinal or cross-rolling units and an inside tool which is used as mandrel bar or piercing plug during the rolling process. The aim is to provide a method to reduce the eccentricity of the rolling stock considerably. To achieve this, the longitudinal axis of the inside tool is forced by means of an apparatus to a movement in a distance to the longitudinal axis of the rolling stock. Simultaneously the rotation of the tool around its axis is kept, driven by the rolling stock during rolling.