Flame correct way construction steel welding deformation What?
Flame Corrective Measures Guangzhou Construction steel welding deformation What?
At present, Guangzhou Steel has been widely used in the plant construction. The steel plant is the main component welding H type steel columns, beams, support. These components are present in the production process of welding deformation, welding deformation if not corrected, will not only affect the structure of the whole installation, but also reduce the safety and reliability engineering.
Deformation occurs over technical design of welded steel promised deformation range, should seek to be corrected, so that it gets fit product quality requirements. Practice has proved that the majority of deformable member is able to correct. Corrective measures are trying to create new arrival deformation counteract deformation occurring now.
Widely used in the production process of redress, there are mechanical correction, correct and comprehensive corrective flame. But the flame is a difficult operation to correct a job, a way to grasp, temperature abuse will result in new and greater deformation member. Therefore, the flame must be corrected wealth of practical experience. This paper made a rough analysis of the type of steel welding deformation remedy.
1, the type of welding deformation of steel and flame corrected
The main component of steel welding H type steel columns, beams, support. Welding deformation often choose three flame remedies: (1) linear heating; (2) dot heating method; (3) heating triangle. Here are ways to solve different parts of the construction.
The following is the correct heating temperature of the flame when (made of low carbon steel)
Low temperature 500 degrees to 600 degrees to correct Cooling: water
The correct temperature of 600 degrees to 700 degrees Cooling: air and water
Correct temperature 700 degrees to 800 degrees Cooling: air
Note: When the flame is heated to correct temperature not too high, too high will cause the metal brittle, impact toughness. 16Mn not be cooled with water at high temperature corrected thickness or contains hardened steel tend to be larger.
Angular Distortion 1.1 flange plates
Correct H type steel columns, beams, support angular distortion. In the upper flange plate (aligned with the outer seam) longitudinal linear heating (heating temperature is controlled at 650 degrees), pay attention to the heating range does not exceed the scope of the control of the two solder feet, so do not use water to cool. When the linear heating to pay attention to: (1) not repeated heating in the same position; (2) the heating process not watering. These two points are correct flame general guidelines.
1.2 columns, beams, braces and arch under torsion and bending
First, the flange plate against longitudinal welds, as from the middle to the ends of the linear heating can correct bending. To prevent bending and distortion, plus two tropical to synchronize. Can be taken to correct the low or medium temperature correct method. This approach helps to reduce welding stress, but such an approach, while longitudinal shrinkage of greater transverse contraction, difficult to master.
Second, the flange plate for linear heating, heating on the web for the triangle. In this way correct columns, beams, bending brace, the effect is significant, the transverse width of the linear heating and generally 20-90mm, thickness h, the heating width narrower, the width of the heating process should be extended to both sides of the middle. Linear heating is preferably carried out simultaneously by two, and then were heated should not exceed the width of the triangle triangle 2 times the plate thickness, corresponding to the base of the triangle and the wing plate width equal to the linear heating. Heating triangle from the top, and then expand from the center to the sides, a layer of heat until the bottom of the triangle up. When the heating temperature is not too high the web, or cause deformation of the recess, it is difficult to repair.
Note: The above approach is equally applicable to heating triangular lateral bending corrected member. Heating should choose the correct temperature, watering less.
1.3 columns, beams, support web wave transformation
Corrective wave transformation we must first find out the raised peak, with dot heating method with hand hammer corrected. Heating dot diameter is generally 50 ~ 90mm, when the plate thickness or undulating area larger diameter should be enlarged, according to d = (4δ + 10) mm (d is the diameter of the heat spots; δ is thickness) calculated value heating. Grilled mouth as from crest spiral movement, the choice of temperature correction. When the temperature reaches 600 to 700 degrees, the hand hammer on the edge of the heating zone, and then the big hammer hand hammer, metal by squeezing the heating zone, cooling contraction after the flare. Should be corrected to prevent large shrinkage stress occurred. After straightening a dot and then heated a second peak point, way above. To speed up the cooling rate of the Q235 steel may be water cooled. This remedy belongs dot heating method, the distribution of heat spots can form dense plum-shaped or chain-shaped point. Watching the temperature should not exceed 750 degrees.
2. Conclusion
Flame correct cause of stress and stress are the same as the welding stress. Not appropriate corrective occurring internal stress and welding stress and load stress superposition, make columns, beams, vertical stress exceeds the promised support stress, thus resulting in reduced bearing safety factor. Therefore, in the manufacture of steel must be careful, try to use reasonable measures to reduce the deformation process, try to correct it if possible use mechanical correction. When forced to choose correct flame should pay attention to the following points:
1. Roast the location can not be near the maximum stress in the main beam cross-section;
2, correct warming himself at a cross-sectional area must not be too large, choose a few to more cross-section;
3, to use the point-like heating methods to improve the stress state of the heating zone;
4, the heating temperature is preferably not more than 700 degrees.
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