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Adjustment of spiral welded pipe unit and characteristics of spiral pipe equipment


The characteristics of the spiral pipe equipment: the straight seam welded pipe production process is simple, the production efficiency is high, the cost is low, and the development is fast. The strength of the spiral pipe production equipment is generally higher than that of the straight seam welded pipe. The welded pipe with a larger diameter can be produced with a narrower blank. The welded pipe of different diameter can be produced with the same width of the blank. The spiral pipe production equipment has a weld length increase of 30 to 100% and a lower production speed than a straight pipe of the same length. Therefore, most of the smaller diameter welded pipes use straight seam welded large diameter welded pipes, and most of them use spiral pipe production equipment.

Several theoretical knowledge of spiral welded pipe equipment adjustment
First, rolling the bottom line
The rolling bottom line is the straight line distance between the center line of the unit and the flat roll throat (the thinnest part), which is the distance between the line and the bottom plate. The height of the rolling bottom line has been determined at the time of shipment from the factory. For example, the bottom line height of the 50 units is 235MM, the bottom line height of the 76 units is 265MM, and the bottom line height of the 89 units is 280MM. This data will vary from manufacturer to manufacturer. The distance from the upper edge of the lower roller ring of the vertical roller to the bottom plate is also the height of the rolling bottom line (the unit whose vertical roller axis is not adjustable).
Second, the starting bottom diameter and bottom diameter increase
The starting point of each unit (the first frame is W variant, the bottom diameter is in the middle of the thickest and thinnest), the bottom diameter (flat roll throat) is also fixed, each increment is 0.6MM-0.8MM, increment The purpose is to make each station rotate slightly faster than the previous one, which belongs to the back and pulls forward, which is beneficial for pipe forming.
Third, the height of the insurance pad
The safety pad is a cast iron cushion placed between the lower slider and the bottom of the arch, and the middle of the pad is pressed into the bottom when the impact is relatively large, so that the shaft is not damaged. The height of the insurance pad is also fixed, and each frame is decremented by 0.3MM-0.4MM (increasing 0.6MM-0.8MM per roll, the pad is decremented by 0.3MM-0.4MM per lot, so the bottom line is still level).
Fourth, the change of the bottom line of the sizing rolling when the circle is changed
When the circle is changed, especially when the circular tube is rounded (flat), the sizing should be adjusted to the center line, and the bottom line is gradually increased. The purpose of this adjustment is to make the pipe evenly deformed and the corners are equal, reducing the impact on the unit. Example: 50*100 rectangular tube (single diameter is five flat and five vertical, four or five times flat roller type), the extrusion roller is out of a circle with a diameter of 94, and the deformation amount is 94-50 when the fourth diameter is fixed. 44MM (When the bottom line is not horizontal, it is equal to 44MM of the upper part of the pipe. When the wall thickness is thick, the impact force on the unit is very large, and the outer R angle of the lower part is rounder than the outer R angle of the upper part. Therefore, the center line should be adopted. Unchanged, that is, the lower flat roller is gradually raised (the rolling bottom line is gradually increased), and when the sizing is performed for the fourth time, 22MM is padded, and the 22MM four pieces are evenly padded (this is a probabilistic algorithm, precisely padded) The data should be a variant of the roll design).

Spiral tube production equipment and its standard classification: spiral submerged arc welded steel pipe (SY5036-83) for pressure fluid transportation is mainly used for conveying oil and natural gas pipelines; spiral seam high frequency welded steel pipe for pressure fluid transportation (SY5038-83) A spiral seam high-frequency welded steel pipe for high-pressure lap welding for the transport of pressurized fluid. The pressure bearing capacity of the steel pipe is good for welding and processing. Generally, the spiral submerged arc welded steel pipe (SY5037-83) for low-pressure fluid transportation is made of double-sided automatic submerged arc welding or single-sided welding for water, gas and air. Submerged arc welded steel pipes for general low-pressure fluid transportation such as steam and steam. The common standards for spiral steel pipes are generally divided into: SY/T5037-2000 (partial standard, also called spiral seam submerged arc welded steel pipe for ordinary fluid conveying pipeline), GB/T9711. 1-1997 (national standard, also called oil and gas industry delivery steel pipe delivery technical conditions Part I: A-grade steel pipe), API-5L (American Petroleum Institute, also called pipeline steel pipe), SY/T5040-92 (pile with spiral burying Arc welded steel pipe)