Coring Control Technology of Stainless Seamless Steel Pipe

The cause of eccentricity of stainless seamless steel pipe can be either one of them or a combination of multiple causes. The design is to ensure that in the extrusion process, to minimize, or even completely compensate for the impact of various eccentric factors. The main measures taken are as follows:
(1) Before pressing, the blank temperature distribution should be checked by means of a temperature detection device arranged along the loading device. The billet temperature change trend will always be displayed on the operator's monitor screen. The temperature change trend is calculated and displayed on the screen so that the operator can adjust the preset value of the induction heating unit accordingly so as to minimize or compensate for the actual detected temperature gradient effect before the start of the extrusion operation.
(2) Whether the extrusion die assembly, the extruding cylinder and the extruding rod are in good alignment shall be checked in real time by the control system during each extrusion; the shaft position shall also be displayed on the screen to indicate that the mechanical equipment In normal working condition.
(3) Use the appropriate material, the use of prestressed technology, to minimize the extruder column tensile deformation. In any case, the extrusion force always produces a minimum elongation. But this elongation will automatically be compensated by the control system in real time by adjusting the position of the squeeze lever.
(4) Good extrusion die quality, but also strictly control the size of steel pipe processing accuracy and access to good surface quality essential to the important conditions. Since the extrusion die is subjected to very high temperatures and pressures, the mold is replaced after each extrusion operation.
(5) A compact glass fiber tray, that is, a glass fiber mat, which can be automatically fitted between the blank and the extrusion die by a robot for surface lubrication of the outer tube wall during the extrusion process.
(6) Use glass fiber lubrication. Only in this way will the metal flow be achieved with almost no friction; and in the contact area, the static friction coefficient can be maintained at a level of 0.03. Through the control system, glass fiber can be automatically distributed and controlled, the density can be controlled at 0.05g / m3 ~ 0.32 g / m3 between. The average diameter of glass fibers is between about 10μm and 15μm. A softened glass fiber (SiO2 · Na2O · CaO) was used which had a viscosity of 103 poise at a temperature of about 1200 ° C. The most desirable is a glass fiber that softens and melts in a narrow temperature range close to the extrusion temperature, resulting in a very good use effect.