General characteristics

Rolling of seamless stainless steel pipes with outside diameter from 30 to 102 mm and wall thickness of 2 to 15 mm is carried out in a special mill. It consists of a core extraction mill, a continuous mill for rolling of the sleeve, a reducing mill working under tension, a calibrating mill and a piercing mill for the production of the sleeve. Only a limited number of tubes - 2-3 are rolled in the continuous mill in order to reduce the stock of expensive mandrels and rolling rolls. Other dimensions of finished tubes are produced through reduction of tubes from this mill.

Rolling technology

The starting material is a round billet. The round billet is first heated and then transferred to the piercing mill, where it is turned into a thermowell after piercing. The hot sleeve is passed from the piercing mill to the continuous rolling mill. A cylindrical mandrel pre-lubricated with inorganic phosphates is pushed into the thermowell. The core with a mandrel is pushed into the rolls of the first stand.

There are nine stands in the continuous mill. Their axes are at a 90° angle. Each stand has a pair of rolls that are driven by a separate electric motor. Even though the rolls are arranged in the same way as in a sizing mill, they are rolled on a mandrel, which increases the length of the tube and reduces the diameter and wall thickness.

The axes of a pair of rolls must be equally spaced. To ensure that the tube is rolled through them at the same time interval, the number of revolutions for each pair of rolls from the first stand to the last one increases with the same progression. Calibration of the rolls provides for a slight stretching of the tube, which does not cause product defects and prevents looping.

The whole rolling in the continuous mill takes 5-9 seconds. The main advantage of this plant is its high productivity. On newest mills, where intermediate operations are mechanized, we can roll at least 300 tubes per hour, i.e. from 60 to 80 tons of metal. After this mill, the tubing is guided by a conveyor to the mandrel extractor, where a mandrel is extracted from it. The mandrel is submerged in a tank for cooling and then returned to the front of the mill. The tube is then passed into a reduction mill (19-stand or 11-stand), where wall thickness and diameter are reduced thanks to the tension between the stands.

Buy, price

Evek GmbH has a wide range of high-quality stainless steel tubes of standard and non-standard sizes in stock. We deliver stainless steel tubes in retail and wholesale. All the lots have the quality certificate on conformity to requirements of standards and technical conditions of operation. The certificate marks the manufacturer, drawing number, alloy grade, melting number, mechanical properties, chemical composition and the results of additional tests. Implementation of orders - in the shortest possible time. Preferential discounts are offered to wholesale customers.