In the cold bending forming equipment, the automatic telescopic type-changing is a technical solution that can quickly adjust the plate shape and shorten the switching time. However, this function is subject to certain limitations due to the thickness of the rollers in practical applications.

1. The basic rule of roller thickness
The common roller thickness is within the range of 20–50mm;
The roller thickness should not exceed 25mm, as exceeding this limit will significantly reduce the expansion accuracy and mold change stability;
For small-diameter rollers, they are usually suitable for processing thinner materials. If attempts are made to process thick plates, the strength and stiffness will be insufficient, and the structure is prone to instability.

2. Limitations of Automatic Stretching and Type Change
Under the condition of 20mm thick rollers, thin plates (such as 0.3–2.0mm) can achieve automatic stretching and rapid type change.
However, when processing thick plates over 3mm in thickness, higher roller stiffness and support force are required, and the automatic stretching structure is difficult to ensure stability and lifespan. Therefore, for the production of large-thickness plates, dedicated rollers or independent units are usually adopted instead of automatic stretching and type change.

3. The Interaction between Width and Thickness
When the product width is small, the diameter and thickness of the rollers are also small → It is more suitable for thin plate forming;
When the product width is large, a larger roller diameter is required → If thick plates are further processed, automatic expansion is difficult to achieve simultaneously.
In other words: The smaller the roller, the less suitable it is for thick plates; The larger the product width, the greater the difficulty of thick plate processing becomes.

4. Insights for Customers
When choosing an automatic stretch-forming and changing machine, it is necessary to consider the specific situation of your own products:
If your main product is thin plates, multiple specifications, and small batches → The advantages of automatic stretch-forming and changing are obvious;
If your main product is thick plates and large structural components → It is more suitable to configure fixed rollers or dedicated production lines.

During the processes of cold bending and stamping, the thickness of the sheet material is a key factor affecting the stability of the process and the quality of the finished product. Sheets of different thickness ranges exhibit significant differences in bending performance and rebound phenomena. Reasonable selection and control of sheet thickness is particularly important for improving the forming accuracy.