Keyword: rolling technology, section steel rolling
Main equipment for section steel production
In the section steel production process, it covers heating furnace, high pressure water descaling, rolling mill, profiler or caliper, shear or saw, thermal printer, cooling bed, straightening machine, marshalling stand, palletizing stand, punching Baler, weighing equipment, spray label and other equipment.
Common defects and control methods of section steel
Section steel angle is not full
Defect characteristics
Due to the insufficient filling of the finished product holes, the lack of metal at the edges and corners of the steel is called the insufficient filling of the steel corners. The surface is rough, some are partial, and some are long.
Cause
(1) Due to the inherent characteristics of the pass, the corners of the rolled piece cannot be processed;
(2) Improper adjustment and operation of the rolling mill, and unreasonable distribution of reduction. The corner reduction is small, or the extension of each part of the rolled piece is inconsistent, resulting in excessive stretching and shrinkage;
(3) The hole type or guide plate is seriously worn, and the guide plate is too wide or installed incorrectly;
(4) The temperature of the rolled piece is low, the plasticity of the metal is poor, and the edges and corners of the pass are not easy to fill;
(5) The rolled piece has serious local bending, and it is easy to cause local corner filling and dissatisfaction after re-rolling.
Control Method
(1) Improve the pass design, strengthen the adjustment operation of the rolling mill, and reasonably distribute the reduction;
(2) Correctly install the guide device, and replace the severely worn pass and guide plate in time;
(3) Adjust the reduction according to the temperature of the rolled piece to make the edges and corners fill well.
Section steel size out of tolerance
Defect characteristics
A general term for section steel sections whose geometric dimensions do not meet the requirements of the standard. When the deviation from the standard size is too large, it appears deformed. There are many names of such defects, most of which are named after the location of occurrence and the degree of out-of-tolerance. Such as out of roundness out of tolerance, length out of tolerance, etc.
Cause
(1) The pass design is unreasonable; the wear of the pass is uneven, and the old and new holes are improperly matched;
(2) The installation of each part of the rolling mill (including the guide and guard device) is poor, and the safety mortar is broken;
(3) Improper adjustment of the rolling mill;
(4) The temperature of the steel billet is uneven, and the uneven temperature of a single piece results in partial inconsistencies in specifications, and the entire length of low-temperature steel produces inconsistencies in specifications, which are too large.
Control Method
(1) Correctly install the components of the rolling mill;
(2) Improve the pass design and strengthen the adjustment operation of the rolling mill;
(3) Pay attention to the wear of the pass type. When replacing the finished product hole, consider replacing the relevant pass type such as the front hole of the finished product at the same time according to the specific situation;
(4) Improve the heating quality of the billet to achieve uniform temperature of the billet.
Steel wave
Defect characteristics
Due to the uneven deformation of rolling, the wave undulations along the length direction of the local section of the section steel are called waves. There are partial ones and long ones. Among them, the longitudinal undulation of the waist of I-beam and channel steel is called waist wave; the longitudinal undulation of I-beam, channel steel and angle steel leg edge is called leg wave. For I-beams and channel steels with wavy waists, the longitudinal thickness of the waists is uneven, and in severe cases, there will be waves of metal overlapping and tongue-shaped hollows.
Cause
(1) Improper distribution of reduction;
(2) The rolls move in series, and the teeth of the rolling groove are wrong;
(3) The front hole or the re-front hole of the finished product is severely worn;
(4) The temperature of the rolled piece is uneven.
Control Method
(1) When replacing the finished hole in the middle of rolling, the front hole of the finished product and the re-front hole of the finished product should be replaced at the same time according to the characteristics of the product and the specific situation;
(2) Strengthen the rolling adjustment operation, reasonably distribute the reduction, and at the same time tighten all parts of the rolling mill to prevent the rolling groove from being misaligned, so that the rolling parts can be extended evenly;
(3) Improve the heating quality of the billet to achieve uniform temperature of the billet.
Section steel cutting defects
Defect characteristics
Various defects caused by poor cutting are collectively referred to as cutting defects. Among them, when flying shears are used to cut small steel in a hot state, scars with different depths and irregular shapes are called cuts on the surface of the steel; in a hot state, the surface is damaged by a saw blade and called sawing; If the surface is not perpendicular to the longitudinal axis, it is called beveling or sawing; if the hot-rolled and shrinking part of the end of the rolled piece is not cut, it is called short cutting; after cold shearing, a local small crack appears on the shearing surface, which is called tearing; sawing (shearing) ) After cutting, the metal flash remaining on the end face of the steel is called burr.
Cause
(1) The sawing steel and the saw blade (scissors) are not perpendicular or the head of the rolled piece is bent too much;
(2) In terms of equipment: the saw blade has a large curvature, the saw blade is not installed properly, and the gap between the upper and lower cutting blades is too large;
(3) In terms of operation: cutting (sawing) too many steel pieces at the same time, cutting too few ends, and not cutting the hot-rolled stretched part.
Control Method
(1) Improve the incoming material situation, take measures to avoid excessive bending of the head of the rolled piece, and keep the incoming material direction perpendicular to the shear (saw) cutting plane;
(2) Improve the condition of the equipment, adopt saw blades with no or small curvature, properly select the thickness of the saw blade, replace the saw blade (scissors) when worn, and install and adjust the shearing (sawing) cutting equipment correctly;
(3) Strengthen the operation, and cut (saw) not too many roots at the same time, so as to avoid the lifting and bending of the steel. Ensure the necessary amount of end cut, and cut off the hot-rolled stretched part.
