ERW Tube Making Machine Operation Series – Part 3: Fine-Tuning the Roll Stands for Optimal Tube Quality

In the previous installments, we covered the initial setup and groove alignment. Now, we’re ready to dive into the fine-tuning process: Adjusting the individual roll stands to achieve the perfect tube profile and a smooth, consistent weld. These steps are critical for ensuring the final product meets your quality standards.

Understanding the Importance of Fine-Tuning

After the initial setup and groove alignment, fine-tuning each of the roll forming stations will ensure accurate and consistent formation of the tube. Each of the key roll stands will be addressed to deliver optimal efficiency and accuracy.

The Adjustment Process

I. Horizontal Roll Stand Adjustments

1. Vertical Positioning: Adjust the horizontal roll stand to raise the center of the bottom shaft to the required position.
2. Vertical Force: Use the adjusting motor to lower the upper shaft, setting the gap between the upper and lower rollers according to the groove diagram.
3. Axial Clearance: Adjust the axial clearance to ensure that the groove centers of the upper and lower rollers are directly aligned with each other to guarantee tube precision.

II. Vertical Roll Adjustments

Adjust the center distance between the two vertical rollers by turning the lead screw to match the roll forming profile of the current pass. If there is skew with the rolling centerline, it must also be adjusted to center it to the line.

III. Guide Roll Stand Adjustments

1. Optimal Positioning: Adjust the guide roll stand to the appropriate position, and adjust the center of the guide rollers to coincide with the rolling centerline.
2. Axial Adjustment: Adjust the axial position of the roll shaft.
3. Opening Angle Adjustment: Adjust the position of the guide roll stand on the worktable to change the opening angle, which facilitates welding.

IV. Squeeze Roll Adjustments

1. Roll Installation: Install the squeeze rolls and the corresponding roll pads.
2. Center Distance Adjustment: The center distance between the two squeeze rolls must be adjusted to match the groove of the squeeze rolls.
3. Centering: If it is found that the groove center does not coincide with the rolling centerline, adjust to center it.

V. Weld Scarffing Device Adjustment

Adjust the tool holder for vertical and horizontal movement so that the cutting edge is aligned with the weld seam of the tube blank being welded.

VI. Rough Straightening Adjustments

1. Reduction Adjustment: Adjust the amount of reduction to suit the finished tube diameter.
2. Positioning Adjustment: Adjust the positions of the horizontal and vertical rollers so that the center of their grooves basically coincides with the rolling centerline.

Preparing for the Test Run

The above adjustments should be made before the test run. Precise adjustments will be made in-situ, so the above steps can be considered a rough starting point. Getting it right starts with a well leveled and smooth line. That means being attentive during the preparation and installation stages will pay dividends.