| 摘要 |
The present invention refers to a method and apparatus for the production of steel bridge-type grooves in a tube. The resulting tube, due to its characteristics, is utilized as a well strut. The tube is also suitable as a structural column and, at the same time, as a sieve or filter, because of the advantageous groove-calibrating features, depending on the material characteristics found in the well. Said calibrating property prevents, together with the gravel placed around the tube, the sand from entering the tube, and consequently, penetrating into the water pump.
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