A method of roll-forming with gap fillers for a solenoid used for a transmission includes the steps of providing a can of a solenoid, the can having a discontinuous surface with a gap, providing additional material in the gap, and roll-forming the additional material in the gap simultaneously with roll-forming the can to maintain a smooth path for rollers during roll-forming for the solenoid.

Sensitive hollow blocks or tubes are elongated in a hot-forming elongator while maintaining, if possible, the internal structure that is present or that forms immediately after casting, and thereby, in the case of suitable method management, even thin-walled tubes or tubes rolled from centrifugally cast hollow blocks can be made available to a sufficiently operationally reliable extent. As a result, for the first time, it is possible for rolled centrifugally cast composite material tubes to be made available and for composite material hollow. blocks produced using centrifugal casting to be utilized for the production of a seamless tube.

Sensitive hollow blocks or tubes are elongated in a hot-forming elongator while maintaining, if possible, the internal structure that is present or that forms immediately after casting, and thereby, in the case of suitable method management, even thin-walled tubes or tubes rolled from centrifugally cast hollow blocks can be made available to a sufficiently operationally reliable extent. As a result, for the first time, it is possible for rolled centrifugally cast composite material tubes to be made available and for composite material hollow. blocks produced using centrifugal casting to be utilized for the production of a seamless tube.

A method for preparing a high-performance difficult-to-deform metal precision seamless pipe includes steps of performing a heat treatment; drilling; externally grinding; internally grinding; straightening; performing four-roller warm-rolling; performing warm-drawing to reduce a diameter; performing warm-expansion to reduce a wall thickness and increase the diameter; performing precise cold-rolling; degreasing; brightening; performing surface grinding; cleaning dust; detecting flaws; testing metal structure performance; and sizing and packaging. By cycling the warm-drawing, the warm-expansion, and the precision cold-rolling, key indicators such as product dimensional accuracy, surface quality, material properties, and crystal grain size can be collaboratively controlled, to achieve higher accuracy, better performance, and more outstanding extreme specifications. Product requirements of different hard-to-deform metal materials and different product specifications can be satisfied, to flexibly prepare metal pipe products with different material characteristics, which greatly improves production efficiency and effectively reduces production costs.

The invention relates to a method for producing seamless pipes of heated massive metal blocks, by means of a mandrel (4), which is fastened on a rolling rod (5), in the case of which a coating material is applied onto the inner side of the hollow block (3) during the forming process by means of the influence of the rolling rod (5) from the massive metal block to a hollow block (3), which is created during the forming.

The invention relates to a method for producing seamless pipes of heated massive metal blocks, by means of a mandrel (4), which is fastened on a rolling rod (5), in the case of which a coating material is applied onto the inner side of the hollow block (3) during the forming process by means of the influence of the rolling rod (5) from the massive metal block to a hollow block (3), which is created during the forming.

A method for producing hot-rolled, seamless pipes having at least one wall thickening which can be arranged at any positions over the length of the pipe, wherein by means of a multiple-stand mandrel bar rolling mill, the rolls roll a hollow shell on a mandrel bar as an inner tool to a required nominal wall thickness and produce at specified positions over the length of the pipe a required wall thickening on the outer side of the pipe by opening the rolls in the rolling stands. The thickened wall is produced and finish-rolled by two rolling stands that are consecutive as seen in the rolling direction, in which the deviations of the finished contour of the thickening from an ideal circular cross-section are minimised, wherein the rolling stands located upstream are likewise opened as to avoid any contact of the rolls of these rolling stands with the previously produced thickening.

A steel pipe for a fuel injection pipe has a chemical composition consisting of, by mass %: C: 0.17 to 0.27%, Si: 0.05 to 0.40%, Mn: 0.30 to 2.00%, P: 0.020% or less, S: 0.0100% or less, O: 0.0040% or less, Ca: 0.0010% or less, Al: 0.005 to 0.060%, N: 0.0020 to 0.0080%, Ti: 0.005 to 0.015%, Nb: 0.015 to 0.045%, Cr: 0 to 1.00%, Mo: 0 to 1.00%, Cu: 0 to 0.50%, Ni: 0 to 0.50%, V: 0 to 0.15%, and the balance: Fe and impurities. The metal micro-structure consists substantially of tempered martensite, or tempered martensite and tempered bainite. The hardness is within the range of 350 to 460 HV1. A lattice spacing of a (211) diffraction plane measured by CoKα characteristic X-ray diffraction is 1.1716 Å or less, and a half-value width of the (211) diffraction plane is 1.200° or less. The number density of cementite having a diameter of 50 nm or more is 20/μm.sup.2 or less.

A method quenches a steel pipe and an apparatus quenches a steel pipe by which a steel pipe having excellent and uniform quality can be acquired by applying uniform rapid cooling to the steel pipe in a longitudinal direction as well as in a circumferential direction of the steel pipe using a simple unit. Movements of a heated steel pipe in a direction parallel to and in a direction perpendicular to a pipe axis of the steel pipe are stopped, and cooling water is jetted onto an outer surface of the steel pipe from four or more spray nozzles arranged spirally outside the steel pipe while rotating the steel pipe about the pipe axis.

A method quenches a steel pipe and an apparatus quenches a steel pipe by which a steel pipe having excellent and uniform quality can be acquired by applying uniform rapid cooling to the steel pipe in a longitudinal direction as well as in a circumferential direction of the steel pipe using a simple unit. Movements of a heated steel pipe in a direction parallel to and in a direction perpendicular to a pipe axis of the steel pipe are stopped, and cooling water is jetted onto an outer surface of the steel pipe from four or more spray nozzles arranged spirally outside the steel pipe while rotating the steel pipe about the pipe axis.