Abstract: A method and apparatus for smoothing a thick walled portion of a steel pipe produced by pressure-welding two opposite longitudinal edges of an open pipe with a squeeze roll after being subjected to induction heating. Outer and inner reduction rollers pressure sandwiches the thick walled portion from the outer and inner surfaces of the pipe, a support supports the inner reduction roller to be rotatable and containing a water passage for cooling water, a connecting rod connects the support device to a coupler and contains a further water passage for feeding cooling water to the water passage, and an anchor holds the connecting rod. In the method of producing steel pipes two opposite longitudinal edges of the open pipe are preformed before being subjected to the induction heating and thereafter a thick walled portion is smoothed by the above-described.

Abstract: A method and apparatus for smoothing a thick walled portion of a steel pipe produced by pressure-welding two opposite longitudinal edges of an open pipe with a squeeze roll after being subjected to induction heating. Outer and inner reduction rollers pressure sandwiches the thick walled portion from the outer and inner surfaces of the pipe, a support supports the inner reduction roller to be rotatable and containing a water passage for cooling water, a connecting rod connects the support device to a coupler and contains a further water passage for feeding cooling water to the water passage, and an anchor holds the connecting rod. In the a method of producing steel pipes two opposite longitudinal edges of the open pipe are preformed before being subjected to the induction heating and thereafter a thick walled portion is smoothed by the above-described apparatus.

Abstract: A forming stand for continuously forming a skelp material into a pipe, by pressure of spaced-apart forming rolls supported by spaced upper and lower shafts, the forming rolls having two portions, with one portion fixedly fitted on one side of its shaft, a sleeve slidably fitted to the other end of the shaft and fixedly secured to the sleeve and slidable with respect to the shaft; a bearing box for supporting one side of the associated shaft; a bearing box supporting the other side of the associated shaft through the sleeve; upper and lower stand supporting frames for supporting both of the bearing boxes to be movable in an axial direction; and supporting columns for supporting the stand supporting frames; the pipe-forming force is continuously measured and the forming operation is adjusted such that the measured value of pipe-forming force does not exceed a predetermined pipe-forming upper limit.

Abstract: A rolling mill comprising a roll unit and a drive unit for driving the roll unit. The drive unit comprises an outer housing, a pair of large-diameter ring-like driving bevel gears disposed concentric with the pass line, an input shaft mechanism for rotating the driving bevel gears, and transmission mechanisms for transmitting the torque of the driving bevel bears to the rolls. Each transmission mechanism comprises a small-diameter transmission bevel gear caught between and engaging with the driving bevel gears and first and second transmission shafts for transmitting the torque of the transmission bevel gear to a roll. The drive and roll units are coupled and uncoupled by couplings. Four positioning parts are formed on the outer periphery of the inner housing of the roll unit. The outer housing of the drive unit is generally in the shape of a ring, and four positioning parts are formed on the inner periphery of the outer housing.

Abstract: A forming stand for continuously forming a skelp material into a pipe, by pressure of spaced-apart forming rolls supported by spaced upper and lower shafts, the forming rolls having two portions, with one portion fixedly fitted on one side of its shaft, a sleeve slidably fitted to the other end of the shaft and fixedly secured to the sleeve and slidable with respect to the shaft; a bearing box for supporting one side of the associated shaft; a bearing box supporting the other side of the associated shaft through the sleeve; upper and lower stand supporting frames for supporting both of the bearing boxes to be movable in an axial direction; and supporting columns for supporting the stand supporting frames; the pipe-forming force is continuously measured and the forming operation is adjusted such that the measured value of pipe-forming force does not exceed a predetermined pipe-forming upper limit.

Abstract: A steel mother pipe obtained by a solid phase butt-welding pipe-making process or a welding pipe-making process is reduced by heating the pipe prior to the reduction at a temperature exceeding 100.degree. C. and lower than 800.degree. C. wherein the temperature of the steel pipe being reduced is controlled within a defined range. The temperature difference along the circumferential direction of the mother pipe at the inlet side of a reducer is within a defined range, and the temperature of the steel pipe at interstand positions of the reducer is also controlled. By virtue of this control, the reduction becomes possible at low load while suppressing work hardening without degrading surface properties. The resultant product pipe has a dimensional accuracy maintained at a high level.

Abstract: A method of producing steel pipes is provided which comprises the steps of providing a steel strip, processing the steel strip into a preheated open pipe, preheating the open pipe at its two opposite longitudinal edges at a temperature higher than about the Curie point, heating the open pipe at the two opposite edges at a temperature higher than about 1,300.degree. C. but lower than the melting point of the steel strip, pressure welding the resultant open pipe with a squeeze roll to thereby form a steel pipe, smoothing the steel pipe at its thick-walled portion formed on an outer surface of the welded seam, and subsequently cutting or winding the resulting steel pipe. An apparatus adapted to form the steel pipes is also provided.

Abstract: In welded pipe manufacturing a steel strip is fed and bent by forming rolls into a pipe. A load detector is provided for a roll rotary shaft of each forming roll; a forming roll inclination adjustment device inclines the roll rotary shaft. The roll shaft load is measured to cause inclining of the rotary shaft counterclockwise or clockwise on a plane formed by the rotational axis of the forming roll and the advancing direction of the steel strip.