How to improve the inner surface quality of seamless steel pipe
Published:
2022-04-28
In order to avoid scarring defects in hot-rolled seamless steel pipes, it is first necessary to learn to use deoxidizers. The oxides are required to be in a molten state when the mandrel is pre-pierced. Its strength and other strict requirements. The particle size of the deoxidizer powder is generally required to be about 16 meshes.
In order to avoid scarring defects in hot-rolled seamless steel pipes, it is first necessary to learn to use deoxidizers. The oxides are required to be in a molten state when the mandrel is pre-pierced. Its strength and other strict requirements. The particle size of the deoxidizer powder is generally required to be about 16 meshes.
The content of sodium stearate in the deoxidizer should reach more than 12%, so that it can be fully burned in the inner cavity of the capillary. According to the inner surface area of the capillary, the injection amount of the deoxidizer is determined, generally 1.5-2.0g/dm2, and the deoxidizer dose is different for different diameters and lengths of the capillary.
Secondly, the injection process parameters of the seamless steel pipe should be reasonably set. The injection pressure should be matched with the diameter and length of the capillary tube, which not only ensures strong purging and sufficient combustion, but also prevents the incompletely combusted deoxidizer from being blown away from the capillary tube by the airflow. The purging time should be adjusted according to the directness and length of the capillary, and it is the standard that no suspended metal oxide in the capillary is blown out.
The nozzle height should be adjusted according to the capillary diameter to ensure good alignment. The nozzles should be cleaned once per shift, and the nozzles should be removed for cleaning after long-term downtime. In order to ensure that the deoxidizer is evenly blown on the inner wall of the capillary, an optional device is used in the spraying deoxidizer station, and it is equipped with a rotary air pressure.
Also, lubricate the mandrel. In order to increase the temperature of the mandrel, the method of cooling with only one cooling water can be adopted. During the production process, it is necessary to strictly control the temperature of the mandrel rod to ensure that the surface temperature of the mandrel rod before spraying the lubricant is 80-120 °C, and the temperature of the mandrel rod cannot be higher than 120 °C for a long time to ensure that the lubricant on the surface is dry and dense before pre-piercing. , the operator should always check the lubrication condition of the mandrel.
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