Cold rolling pipe manufacturing method for improving roughness quality of inner wall of stainless steel seamless pipe for power station boiler

Abstract

A cold rolling pipe manufacturing method for improving the roughness quality of the inner wall of a stainless steel seamless pipe for a power station boiler adopts a two-pass cold rolling deformationprocess to roll to obtain finished pipes for delivery, that is, an LG-80 or LG-110H cold rolling mill is adopted for cogging rolling and an SKW-75 high-speed cold rolling mill is adopted for rolling to obtain the finished products. Meanwhile, by optimizing parameters such as a roller device, a hole pattern and a core rod related to cold rolling deformation and taking measures such as increasing the diameter of the core rod, widening a hole pattern opening and reducing a movement gap, the cold rolling pipe making quality and efficiency of the stainless steel seamless pipe for the power stationboiler are improved. On the basis of meeting the technical requirements for cold rolling of the boiler pipe of the power station, the quality loss of the roughness of the inner wall caused by abnormalworking conditions such as "top punching" and "insufficient rotation" of a pipe blank is reduced, the yield is increased, and the production cost is reduced.

Description

technical field [0001] The present invention relates to a method for making seamless steel pipes, especially a cold rolling method for improving the inner wall roughness quality of stainless steel seamless pipes for power plant boilers, which is especially suitable for thick-walled pipes of power plant boilers with a finished product wall thickness greater than 5mm at room temperature Production and processing of cold-rolled tubes. Background technique [0002] Seamless steel pipes are common metallurgical metal products. The seamless steel pipe cold rolling technology has become the main method of seamless steel pipe production and preparation because of its high rolling precision, fast speed, large production capacity, high yield, and easy adjustment of production organization and process technology. [0003] The two-roller periodic cold-rolling mill is currently the most commonly used cold-rolling equipment for seamless steel pipes. It is composed of hydraulic system, p...

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Problems solved by technology

[0008] At present, in the production of cold-rolled stainless steel seamless pipes for power plant boilers, since most of these seamless steel pipes are thick-walled pipes with a wall thickness of more than 5mm, the billet is large and the axial movement is large. In this process, the axial "top punching" of the tube blank and the mandrel head and the abnormal synchronous rotary motion of the tube blank (not moving) are caused. This is the main factor affecting the roughness of the inner wall, and the result is that the product quality is unqualified.

[0009] 1) The "top punch" phenomenon is a common phenomenon in the cold rolling process of seamless steel pipes, especially in the rolling process of thick-walled pipes. The reason is that the deformation of the billet pipe is too concentrated in the deformation zone, causing rolling The force increases, causing the roller device to jump up and down due to the working clearance of the bearing, and finally leads to a large impact load or an instantaneous increase in the impact load when the working frame (together with the roller device) is at the front and rear limit positions , causing the billet tube being rolled to move forward

The consequence is damage to the rolling surface quality. If it is at the junction of the front and rear billet tubes at this time, it is easy to cause an incarceration fault between the billet tubes

[0010] 2) The phenomenon of "insufficient rotation" is limited to the rolling process of thick-walled tubes. In addition to the fault defect of the equipment's feeding and rotating mechanism, most of the reasons are due to the single weight of the tube billet, which increases the hindrance of the mandrel's synchronous rotation. caused by

As a result, the roundness of the seamless steel pipe is directly abnormal, and it is easy to cause defects such as edges and corners, rolling folds, and "ears" on the rolling surface.

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