Precise control the wall thickness and diameter of seamless pipes

The precision control of wall thickness and diameter is crucial for ensuring the quality and performance of seamless steel pipes. Achieving this precision requires a combination of advanced technologies and methods. Below, United Steel Industry Co., Ltd. has summarized the main techniques for controlling the wall thickness and diameter of seamless pipes.

Factors Affecting Wall Thickness and Diameter

Tube Quality:
The size, shape, and uniformity of the tube directly influence the final wall thickness and diameter of the steel pipe.

Heating Temperature and Uniformity:
Uneven heating can cause irregular deformation during piercing and rolling, impacting both the wall thickness and diameter.

Punching Process and Parameters:
Factors such as the puncher's adjustment, plug positioning, and roller parameters affect the rough tube's wall thickness and diameter.

Rolling Process and Parameters:
The settings of the rolling mill, roller shape, speed, and tension all play a role in determining the pipe’s wall thickness and diameter.

Sizing Process and Parameters:
The adjustments made to the sizing machine and roller shape directly influence the final outer diameter of the steel pipe.

Cooling Process:
The speed and uniformity of cooling can lead to dimensional changes in the pipe, affecting both thickness and diameter.

Methods for Controlling Wall Thickness

Precision Control of Tube Blanks:
Use high-precision continuous casting or rolling techniques to ensure the tube billet's size and shape accuracy. Strict inspections help eliminate defective billets.

Optimizing the Heating Process:
Employ advanced furnaces, such as ring heating furnaces or walking beam furnaces, for uniform heating. Temperature control systems ensure the tube billet is heated within the optimal range.

Control of the Perforation Process:
Careful selection and precise adjustment of the perforator and punch are essential. Parameters like roll speed and feed speed should be closely controlled to achieve the desired wall thickness.

Advanced Rolling Technology:
Use cutting-edge rolling mills like PQF continuous rolling mills and ACCU-Roll planetary rolling mills to enhance rolling precision. Automated systems manage parameters such as roll spacing, speed, and tension. Tension reduction technology further refines wall thickness control by adjusting the working diameter of the rolls during tension reduction.

Online Wall Thickness Measurement:
Real-time monitoring using online wall thickness measuring instruments ensures precise control. These instruments perform continuous multi-point scanning, even under high temperatures, allowing for closed-loop adjustments to the rolling parameters.

Methods for Controlling Diameter

Control of Tube Blanks and Piercing:
The diameter of the tube blank and the rough tube after piercing directly affect the final steel pipe diameter.

Precision Control of Rolling Process:
The outer diameter is controlled by adjusting the spacing and shape of the rollers.

Sizing Technology:
Sizing mills or stretch reducers are used to precisely control the final outer diameter of the steel pipe.

Online Diameter Measurement:
Real-time monitoring with online diameter measuring instruments ensures accurate diameter control. Adjustments to rolling or sizing parameters are made based on the measurement results.

Additional Auxiliary Methods

Heat Treatment:
A well-designed heat treatment process minimizes dimensional changes during the cooling phase of production.

Accurate Measuring Tools and Methods:
High-precision tools, such as vernier calipers and micrometers, are essential for accurate measurements, allowing for real-time adjustments to meet specifications.

Quality Management System:
A robust quality management system ensures that all production parameters remain within the prescribed control range, guaranteeing the consistency and reliability of the pipes.