The production process
(1) raw materials are strip coil, wire and flux. Strict physical and chemical tests are required before input.
(2) butt joint of strip steel head, single wire or double wire submerged arc welding is adopted, and automatic submerged arc welding is adopted after rolling steel pipe.
(3) before forming, the strip shall be straightened, trimmed, planed, and the surface cleaned and transported and treated with bending edges.
(4) use the electric contact pressure gauge to control the pressure of the oil cylinder on both sides of the conveyor, ensuring the smooth delivery of the strip.
(5) adopt external control or internal control roller forming.
(6) the weld clearance control device is adopted to ensure that the weld clearance meets the welding requirements, the pipe diameter, the wrong side quantity and the weld clearance are strictly controlled.
(7) both internal and external welding are used for single wire or double wire submerged arc welding in the American Lincoln welding machine to achieve stable welding quality.
(8) the welded seam is checked by the on-line continuous ultrasonic automatic injury machine, which guarantees the nondestructive testing coverage of 100% spiral welds. If there are defects, automatic alarm and spray mark, the production workers can adjust the process parameters at any time, and eliminate the defects in time.
(9) use air plasma cutting machine to cut the steel pipe into single root.
After cut into single pole (10), the head of every batch of steel pipe should be strictly check system, check the weld mechanical properties, chemical composition, amalgamation, steel tube surface quality and the nondestructive flaw detection, ensure that qualified pipe process, can be formally put into production.
(11) have continuous acoustic detection of weld mark parts, after manual ultrasonic and X-ray check, if there are defects, after repair, again through the nondestructive inspection, until defects have been eliminated.
(12) the tube of the weld joint with the weld joint and the joint with the spiral weld shall be inspected by X ray TV or film.
(13) each steel pipe is tested by hydrostatic pressure, and the pressure is sealed in radial direction. The test pressure and time are strictly controlled by the microcomputer testing device. Test parameter automatic printing record.
(14) the pipe ends are machined so that the end face is perpendicular, and the groove Angle and blunt edge are controlled accurately.
Fold weld treatment
1. If the gap is too large, the adjacent effect will be reduced, and the eddy current heat is not enough.
2. If the clearance is too small, the proximity effect will increase, and the welding heat will be too large, resulting in the weld loss. Or the weld is extruded, rolled and formed deep pit, affecting the weld surface quality.
When the two edges of the tube are heated to the welding temperature, the common metal grains penetrate and crystallize, forming a solid weld at the end of the extrusion roll. If the extrusion pressure of spiral steel tube is too small, the number of common crystals will be small, and the strength of the weld metal will decrease, which will cause cracking after stress. If the extrusion pressure is too high, the molten metal will be extruded, which not only reduces the weld strength, but also produces a large number of internal and external burrs, and even defects such as welding seams.