The pressure frame of the beam straightening machine is a half-split structure, which can adjust the upper straightening roller set to compensate for the deformation of the upper frame and correct the wave shape of the steel plate. Fully automatic control of the straightening process is achieved by presetting the model. The upper straightening roller set can be opened quickly by the hydraulic overload protection. The lower straightening rollers at the entrance/exit can be adjusted up and down independently. At the same time, it is also equipped with iron oxide scale collection and dust removal devices.
1. Check and adjust
(1) Before running the beam straightening machine, it is necessary to check the parts of the equipment and the lubrication system in detail, check whether the hydraulic system works normally, check whether the oil and gas system and the cooling system are put into operation, check whether the main drive conditions are satisfied, the running state is good, and the screws in all parts are checked. There should be no breakage and looseness to ensure that the cooling system works well.
(2) Run the empty car for 1 to 2 minutes, check the operation, and require the backup roll and the work roll to be in close contact and all rotated.
(3) Before the steel plate enters the beam straightening machine, the surface foreign matter must be removed.
(4) Check the work rollers, front, and rear roller tables, and front and rear guard plates of the beam straightening machine. There should be no iron sheets, burrs, and other debris that scratch the steel plate, otherwise immediate measures should be taken to remove them.
(5) Adjust the roll gap of the beam straightening machine according to the thickness of the straightening steel plate.
2. Straightening operation requirements.
(1) Understand the work plan on the shift, adjust the roll gap of the beam straightening machine in time according to the rolling specifications, pay attention to the changes in the specifications of the steel plate at any time, and strictly prevent accidents caused by correcting the specifications. In the case of automatic mode, if the parameters given by the model are found to be unreasonable, it should be changed to manual mode immediately, and reasonable parameters should be set to prevent straightening accidents.
(2) Straightening temperature: 450～1000℃
(3) It is not allowed to adjust and press down with the load.
(4) The steel plate shall not enter the beam straightening machine skewed, and the steel plate with serious scraping, folding, uneven thickness, and burr cut by gas shall not enter the beam straightening machine for straightening.
(5) Do not allow double steel plates or overlapping steel plates to enter the beam straightening machine.
(6) Under normal circumstances, the beam straightening machine straightens one pass. When the individual plate shape is not good, the pass number can be appropriately increased.
(7) When the temperature of the rolled piece is lower than 500 ℃, the reduction amount should be reduced and the straightening should be carried out at a low speed.
(8) Pay attention to observing the quality of the plate surface. If the "straightening and imprinting" of the steel plate after straightening is found, it should be stopped immediately for inspection and treatment.
(9) When the steel plate is transported from the roller table to the cooling bed, it is not allowed to overlap, skew and overlap, and it should be sent flat one by one.
(10) When there is a steel plate on the cooling bed input roller table or the cooling bed lifting mechanism is transporting the steel plate, it is not allowed to convey the steel plate to the cooling bed input roller table.
Common defects in the steel straightening process include finished product bending, torsion, wave, straightening, etc. In actual production, the following corresponding measures are mainly taken to solve.
(1) The finished product is bent.
Bending is further divided into up and down bending and left and right bending. According to the requirements, the bending degree of section steel per meter is ≤ 3mm, and the total bending degree is ≤ 0.3% of the total length. Exceeding this range is an unqualified material. After long-term production practice, the main reasons for the vertical bending of the straightened steel are analyzed. First, the pressure distribution of the upper and lower rolls is inappropriate. Second, the pressure distribution of the first and second rolls is too small and does not exceed the yield limit of the steel itself, which makes the steel be After straightening, the original bending degree is still maintained. The corresponding measures taken are to adjust the pressure distribution relationship between the upper five rollers, increase the pressure distribution of the first and second rollers, and increase the straightening force of the beam straightening machine. The main reason for the left and right bending of the steel is the misalignment of the straightening pass, and measures are taken to adjust the pass of the upper and lower rolls to make it completely aligned.
(2) The finished product is twisted.
The main reasons for the torsion of the steel after straightening are the small pressure distribution of the upper roll system and the dislocation of the straightening pass. In this regard, the measures adopted are to appropriately increase the pressure value of the upper roller and to observe the alignment of the upper and lower rollers to avoid dislocation.
(3) Finished wave bend.
The wave bend is divided into two types: waist wave and leg wave. The main reasons for the generation of waist waves are: the working diameter of the adjacent straightening rollers is too different; the straightening hole processing does not make the straightening roller out of round or the assembly gap is too large, and the straightening roller jumps during the rotation process; the pressure of the upper roller system The distribution is unreasonable. In this regard, the usual measures are: to check the use of the straightening rolls, confirm the diameter deviation of each roll, adjust the position of the straightening rolls appropriately or directly replace the rolls that do not meet the requirements and redistribute and adjust the pressure of the upper rolls at the same time. The main reason for the leg wave is the dislocation of the straightening roller hole pattern and the large axial movement. The general measures taken are to re-align the straightening roller and check whether the installation of the equipment meets the process specifications to eliminate the axial movement.
(4) Correction of finished products.
Straightening is the situation in which the surface quality of the finished steel is unqualified due to the straightening process. The main reasons for the straightening of the steel are a large amount of wear of the straightening hole type, which is not replaced in time, which makes the surface quality of the steel worse; the surface of the straightening roller that contacts the steel has foreign objects (such as steel slag, sticky skin, etc.), and the straightening process Pressed into the steel surface, the steel produces surface scarring defects; the straightening roll pass is dislocated, resulting in obvious straightening marks on the steel surface. In order to avoid the defects of straightening, the measures adopted include replacing the straightening roller in time, checking whether there is foreign matter on the roller surface, frequently aligning the hole pattern, etc.