Abstract: The invention relates to a method for producing seamless tubes from metal, particularly from steel, wherein a previously produced hot hollow block is stretched by means of a three-roll bar rolling mill on a mandrel to form a parent tube and, before running into the bar rolling mill, the hollow block is provided with a rolling step that makes the diameter more uniform by means of an upstream stand. It is in this case provided that the rolls of the upstream stand are moved apart and together to the same extent as the deforming stands of the bar rolling mill, wherein the calibrating base radius of the rolls of the upstream stand extends over 60° and this is followed by a flank radius with a tangential transition which is dimensioned such that even with the maximum setting of the rolls in the region of the flank there is virtually no diameter reduction of the largest hollow block diameter to be expected.

Abstract: The invention relates to a method for producing seamless tubes from metal, particularly from steel, wherein a previously produced hot hollow block is stretched by means of a three-roll bar rolling mill on a mandrel to form a parent tube and, before running into the bar rolling mill, the hollow block is provided with a rolling step that makes the diameter more uniform by means of an upstream stand. It is in this case provided that the rolls of the upstream stand are moved apart and together to the same extent as the deforming stands of the bar rolling mill, wherein the calibrating base radius of the rolls of the upstream stand extends over 60° and this is followed by a flank radius with a tangential transition which is dimensioned such that even with the maximum setting of the rolls in the region of the flank there is virtually no diameter reduction of the largest hollow block diameter to be expected.

Abstract: A method of manufacturing seamless pipes having medium-thick or thin walls from an elongated hollow body of limited length which is reshaped by rolling to the desired final dimension, as well as a rolling apparatus for the carrying out of the method. This method of manufacturing seamless pipes having medium-thick or thin walls from an elongated hollow body is characterized by the fact that, with only one rolling pass the diameter of the hollow body is significantly reduced and by using an inner tool the inner surface is smoothed with only a slight change in wall thickness. Further, this method allows for the rolling of the axis of the hollow body to align with the axis of rolling. The rolling apparatus includes an inner tool which cooperates with two rolls to reduce the diameter of the pipe to a desired final dimension, the two rolls each having an inlet part, a feed part, a reducing part inclined at an angle within the range of more than 2.degree. and up to 10.degree.

Abstract: Seamless tubing and pipes are made from solid rounds with a diameter not exceeding 0.8 of the diameter of the tubing or pipe to be made; the method includes the steps of piercing the solid with a mandrel such that a conical widening angle at the end of piercing has a particular value; a smoothing step is provided downstream from the piercing also with a particular cone angle; and between the piercing and the smoothing of the now pierced hollow is widened under reduction of the wall thickness at a conical angle of widening that is larger (blunter) than the widening angle of piercing and the particular cone angle.

Abstract: It was discovered that a rolling mandrel holding a hollow which is rolled in a multistrand mill should be advanced in a particular manner that relates to the stretching the hollow undergoes in the first and second stand, as well as to the speed of the unrolled hollow. A velocity profile has been developed accordingly.

Abstract: The method of gaplessly separating and identifying successive rolling lots of ingots or blooms in a production process for making tubes or the like wherein the stock is introduced into a furnace for heating and in a production line subsequently rolled, which comprises radio-actively marking the first or the last ingot of a given rolling lot of ingots at its subsequently lost end prior to being introduced into the furnace. A further step includes interposing a radio-active radiation responsive signal device in said production line before rolling. Apparatus for carrying out said method includes a device for imparting radioactivity to an ingot in advance of a rotary hearth furnace. Radiation counter-tubes are located in advance of a taper mill and a continuous rolling mill respectively. Further counter-tubes are arranged in advance of a stretch reducing or sizing mill.