How does the first half of ERW high frequency welding work?

Posted by zora li on May 24th, 2023

How does the first half of ERW pipe high frequency welding work?

Typical process of high frequency welded pipe:

Feeding—inspection—shear butt welding—loop storage—forming—high frequency welding—deburring—cooling—flaw detection—sizing and straightening—fly cutting—intermediate inspection—extracting inner burrs—flat end chamfering—packing and storage .

1. Loading inspection (open book)

1.1 Before and after uncoiling, the steel grade or designation of the narrow strip should be inspected, and the equipped measuring tool should be used for random inspection (at least once/a large steel coil). ×thickness); when the second furnace/batch number is used for the steel grade used in the same welded pipe specification due to the large batch size, the production batch must be listed with a single sub-batch number, and mixed batch numbers are strictly prohibited;

1.2 When hoisting the narrow-strip steel coil to the uncoiler, the direction of the burr on the longitudinal edge of the narrow-strip steel should face upward.

1.3 The narrow-strip steel coil is hoisted to the uncoiler, and the mandrel of the uncoiler must tighten the inner diameter of the narrow-strip steel coil to prevent the narrow-strip steel coil from falling apart during uncoiling and discharging; It can move and be linked with the looper to prevent the uncoiler from dropping the belt or the end of the belt into the looper during filling" function;

1.4 The specifications and steel grades of the steel strips should meet the requirements of the production specifications of welded pipes on duty, and each coil of steel strips needs to be inspected and complies with the requirements of the "Narrow Strip Steel Feeding Inspection Standard Book".

1.5 It is necessary to carry out visual inspection on the surface and longitudinal shear surface of the narrow strip steel, and meet the requirements of the "Sample Loading Limit". If any abnormality is found, it should be dealt with according to the operation instruction.

2. Shear butt welding

2.1 It must be confirmed that the direction of the burr of the narrow strip is upward;

2.2 During butt welding, about 3mm of arc starting and arc ending are left on both edges of the narrow strip in the width direction, and the remaining welding gap joint material is just enough to remove the arc-shaped cutting surface of the inner burr, reducing the possibility of damage to the inner burr blade;

2.3 The edges of the butt-connected narrow strips in the width direction need to be aligned as much as possible, and there should be no height in the thickness direction. It is best to grind the weld joint after welding.

3. Looper storage

3. The pinch roller is only used for 1-speed charging, and the rotation of the storage tray is used to roll the tape into the material tray during low-speed or uniform filling;

3.2 For soft materials, inclined rollers with smaller angles and transition rollers with lower heights are used, while for hard materials, the opposite is true.

4. Extrusion

4.1 Feed centering adjustment ① The reduction of W roller will directly affect the forming quality, ② The symmetry of the tube in front of the extrusion roller and the height of the weld, ③ The quality and smoothness of removing internal and external burrs, etc.;

4.2 After the centering adjustment of the feed material, the flowing water interface of the narrow strip passing through the arc surface of the tube of the W roller is basically consistent; from the W roller to the squeeze roller, the welds on both sides of the tube basically form two symmetrical taper lines, no wavy bends;

4.3 Soft material adopts open-type reduction to adjust "W roller just touches the strip steel or slight reduction", and there is no obvious indentation on the arc-shaped inner surface of the tube; hard material, including hot-rolled coils with small diameters, adopts Closed reduction adjustment "W roller contact strip steel or larger reduction", there is no obvious indentation on the inner surface of the arc of the tube; larger reduction is not good for the forming quality, especially for the finished product with an angle of 45° It is difficult to adjust the size in the sizing section; when the flaring ≥ 35% after welding and the flattening 2t test fails, the fine forming section can be adjusted by open pressing.

4.4 When making welded pipes for hot-rolled coils, a large amount of water must be used to wash away the oxides next to the W roll.

The horizontal rolls and vertical rolls after 4.5 are also adjusted by open or closed pressing. Special attention should be paid to the fact that the vertical rolls only play an auxiliary role in the forming quality. For soft materials, manual adjustment is enough, and a certain amount of pressure is added at most. Preload! For hot-rolled coils, the vertical rolls must be tightened to achieve stable edge formation.

4.6 The surface of the tube after rough forming has no edges and corners, which is beneficial to the subsequent adjustment of the extrusion roller and the sizing section; if the edges and corners of the tube surface cannot be eliminated, the 45° angle of the sizing size will remain.

4.7 When the head of the tube blank is deformed and has burrs, it must be removed and must not be fretted to pass through the rough forming machine, and it is absolutely not allowed to enter the fine forming machine;

4.8 When the pass size of each pass of the fine forming horizontal roller is not adjusted to the specified size, it is not allowed to pass through the fine forming machine and enter the "welding squeeze roller";

4.9 Before the tube tube enters the "welding squeeze roller", the weld seam on both sides of the tube tube to be welded is not allowed to be uneven, nor is it allowed to appear distortion of the tube seam and waves or bulges on both sides of the tube seam ; Must be aligned in parallel, continuously and stably enter the "welding extrusion pass";

4.10 After being adjusted by the forming machine, the formed tube should have a basic and correct cylindrical shape, a size that meets the adjustment regulations, and sufficient "extrusion" (OD+0.45~0.8); Internal and external lap welding phenomenon, the internal and external burrs formed by welding extrusion should be a smooth and uniform welding rod;

4.11 After start-up and trial welding, take samples for "technical performance test: flaring and flattening" and the results must reach and meet the "specified value" of the implementation standard of welded pipe specifications for on-duty production;

4.12 After start-up and test welding, the inspection of "internal burr residual height and quality" must be carried out by sampling, which must reach and meet the "prescribed value" of the implementation standard of welded pipe specifications for on-duty production, and there is no internal lap welding;

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zora li

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zora li
Joined: August 16th, 2022
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