Hot forming of conical tubes made of hardening materials, comprises heating the tubes, forming the tubes in a pressing tool, and partially cooling an external- and internal surface of the tube

摘要

The process for hot forming conical tubes (2) made of hardening materials, comprises heating the tubes, forming the tubes in a pressing tool (1), and partially cooling an external- and internal surface of the tube. A first control for cooling the tube is carried out on the first part of the tube at a cooling speed of 27-100[deg] C/second and at a temperature of 900-250[deg] C thus allowing the hardening of the material. The internal surface of the tube is cooled by injecting a coolant fluid under pressure in a cavity of the tube. The coolant fluid flows through channels with controlled temperature. The process for hot forming conical tubes (2) made of hardening materials, comprises heating the tubes, forming the tubes in a pressing tool (1), and partially cooling an external- and internal surface of the tube. A first control for cooling the tube is carried out on the first part of the tube at a cooling speed of 27-100[deg] C/second and at a temperature of 900-250[deg] C thus allowing the hardening of the material. The internal surface of the tube is cooled by injecting a coolant fluid under pressure in a cavity of the tube. The coolant fluid flows through channels with controlled temperature, and is water, air, oil, air/water mist, air/oil mist, salt in aqueous solution and a gas supplied to the pressing tool. A second control for cooling the tube is carried out on a second part of the tube at a cooling speed of 5-15[deg] C/second and at a temperature of 900-550[deg] C by heating the pressing tool. The tubes are formed by joining two initial tubes each comprising outer and inner sections. The inner sections of the two initial tubes are identical while the external sections are different, and vice-versa. A sealing unit is arranged for insulating two sections of the tube before heating the pressing tool. An independent claim is included for a device for hot forming conical tubes made of hardening materials.