banner
Mar 19, 2021
44 Views
Comments Off on The problem and solution of bar four-cutting, bar wire technology

The problem and solution of bar four-cutting, bar wire technology

Written by
banner
  • Slitting knife sticks to steel

The sticking of steel on the slitting knife refers to the phenomenon that the two sides or one side of the slitting knife stick to the slag during the slitting and rolling production process, which will eventually lead to the failure of the slitting. The main reasons for the sticking of the slitting knife are as follows:

 

  1. The rolling temperature is too high. If the opening temperature is too high, during the cutting process of the finishing rolling zone, when the reduction of the cutting wedge is very large, a large amount of heat is generated due to the sharp deformation, which causes the local metal temperature to rise rapidly and the shape of the cutting strip is irregular, causing The slitting knife sticks to steel.
  2. If the incoming material is too large or too small, the slitting and rolling follows the axe principle, and the incoming material must match the angle of the 16-frame slitting wedge. 15 If the shape of the material is too large or too small, it will cause difficulty in cutting, resulting in excessively large slitting belts. During the advancement of the rolling piece, friction between the slitting belt and the slitting knife will cause steel sticking.
  3. The slitting wheel is off-track or misaligned with the rolling groove. The installation of the splitting guide guard must ensure that the splitting wedge, the splitting wheel, and the splitting knife are three points and one line. The alignment is good. If the installation is not correct, the material and the cutting wheel cannot be aligned and the cutting is off, causing the cutting belt to be too large, and friction with the cutting knife, causing steel sticking.
  4. The slitting knife is not cooled well, and the slitting guide must ensure sufficient cooling, especially the slitting knife. During the normal production process, due to the wear of the billet and the rolling groove, the surface of the rolling piece has a small oxide scale and the shape of the slitting strip. Irregular, friction with the slitting knife sticks on both sides, if the cooling effect is not good, it will stick more and more, and eventually lead to rush out of the guide pile steel, and the downstream rolling mill cannot be adjusted.
  5. The slitting knife spacing is not appropriate. After the rolling piece enters the slitting box, it will be at a certain angle. If the slitting knife spacing is not set, the rolling piece will rub against the slitting knife and stick to the steel.
  6. The splitting hole design is unreasonable. The design of the 15-16 rack hole pattern system is very important, and the splitting angle design must match.
  7. The rolling mill has poor rigidity, large bouncing, and poor material shape control.
  8. The length of the slitting knife is inappropriate, and the three slitting is more obvious. Too close to the slitting wheel will cause inconvenient slag discharge and cause sticking of steel.
  9. The angle design of the splitting wheel is unreasonable and the splitting is not smooth.
  10. The shape of racks from 12 to 18 is not well controlled, and the material will be twisted obliquely, too large or too small, and the head is large and the tail is large, causing stickiness and rigidity.
  11. There is a problem with the billet itself, which contains air bubbles and blooms.
  12. The rolling groove of the key train is aging or jumping out of the groove.
  13. The guide beam and the guide guard of the key sorties are not aligned with the rolling center.
  14. The tension of each flight is not well controlled or the temperature is not stable.
  15. The guide plate or guide plate is excessively worn or the guide groove assembly is faulty.

Slitting knife sticking steel solution

  1. The steel temperature should be controlled according to the process requirements. When the load of the main motor is satisfied, the steel temperature should be controlled at 1000 to 1050 degrees Celsius, preferably not more than 1100 degrees Celsius.
  2. Strictly control the size of the good material type according to the process requirements. The size deviation of the rough rolling six stands is controlled within ±0.5 mm, the medium rolling dimension deviation is controlled within ±0.3mm, and the finish rolling dimension deviation is controlled within 0.2 mm. The pre-cutting and cutting sorts should be strictly controlled in accordance with the technological requirements. Ensure the fullness of the split sorties.
  3. The installation of the slitting guide should be accurate, keeping the slitting knife, slitting wheel, and slitting groove in the same straight line, and at the same time strengthen the cooling of the slitting guide and rolling groove, and observe the degree of turning steel of the material type in time. The designer must do a good job of design proofreading for the hole pattern.
  4. The spacing of the slitting knives is certain, carefully check whether the spacing of the slitting knives is appropriate.
  5. Control the material type of each pass as required.
  6. Make an online inspection of the rolling line in time. Install the guide guard and guide guard beam correctly.
  • The problem of the four-line difference of the slitting rolling line

Although the slitting rolling process has effectively increased the operating rate and increased the output significantly, it is affected by various factors such as steel temperature fluctuations, rolling groove wear, pass system design, guide and guard installation, and rolling groove processing accuracy. The size of the parts can not be exactly the same, that is, there is a line difference. If the quality of the steel is required to obtain higher economic benefits, this requires various means to narrow the gap between the lines. The main reasons for the line difference are as follows:

  1. The imported guide guards for pre-cutting 15 racks or cutting 16 racks are not aligned with the rolling line and are biased to one side. At this time, the side that is biased after the incoming material is cut is large due to the large cross-sectional area, resulting in a large size of the finished line.
  2. The hole type wear is inconsistent. Due to the inconsistent cooling of the rolling groove, the irregular shape of the previous pass or the design of the guide and guard pass, the cross-sectional area of ​​the severely worn line will increase, resulting in the size of the finished product.
  3. The roll gap on both sides is inconsistent. During the roll-changing adjustment, due to the inconsistent roll gap control on both sides of the 15-18 racks, the hole area on the side with the larger roll gap is larger, which leads to differences in the finished product.
  4. The processing precision of the rolling groove is not high. This is mainly related to the material of the roll, the wear and repair accuracy of the forming tool in the repair workshop, and the processing method.
  5. There is a problem with the material shape control of the 12-16 sorties. Slicing production pays great attention to the matching of 12-16 sorties. If the matching is not good, it will cause line difference.
  6. The main reasons for the line difference are generally concentrated on the aging of the K4 rolling groove, the alignment problem with the K3K4 guide and guard, and the K6 material shape change problem.

The solution to the four-wire difference

  1. Install guide and guard accurately. Before changing the rollers, the guide and guard must be pre-adjusted to ensure that all positions are aligned and fixed.
  2. Improve 15, 16 cooling water pipes, strengthen the cooling effect, and do a spot check during the production process.
  3. Start the rolling mill when changing rolls, measure the roll gap on both sides with the same welding rod, and control the deviation within 0.1mm.
  4. Improve the material of the rolls, use high-speed steel rolls for 15, 17, 18. Contact processing department to improve processing accuracy.
  5. Control the shape of each pass in strict accordance with the process requirements, and adjust the guide and guard gap with the sample bar as required.
  • 18 rack top exit failure

During the slitting and rolling production process, the failure of the top outlet of the 18 stand is more common, which is a major failure point that restricts the four slitting production. It is mainly manifested by the sharp bending of the front end of the inner or outer two-wire steel in the direction of the slitting belt, and the pipe The tip of the tongue falls off, or bends 180 degrees and rushes out from the exit to be stuck in the guide groove to pile steel. The main reasons for this phenomenon are as follows:

  1. There are defects in the pass design, mainly due to the problems in the allocation of parameters during the pass design, which makes adjustments too difficult and requires extremely high requirements for the overall quality and operational level of employees.
  2. The design of the 17-frame hole-shaped slot is too large, and the slitting belt cannot be processed well.
  3. Inaccurate control of material shape. 15 racks are not fully filled, or the shape of 16 racks is too small, the front ends of the two lines are severely asymmetric after cutting, the deformation of the 17 racks is uneven, and the slitting belt is not processed well, and the ejection phenomenon occurs when entering 18 racks, or The shape of the 12-16 racks is too large, and the 18 racks are deformed severely and unevenly, causing the ejection phenomenon.
  4. Inappropriate control of the guide and guard clearance of 15 racks and 16 racks is not good for neutrality. The front end of the rolling piece is bent and cut off when cutting, causing the head size to be too large or too small. After 17 racks, the top exit of 18 racks is caused.
  5. The temperature at the slitting belt is relatively high, and it is not easy to get out of the groove on the 18 racks.
  6. There is a problem with the guide and guard design or the size of the outlet cavity of the 18 racks is too large, which is relatively far away from the roll, which cannot effectively prevent the head shape change of the 18 racks.
  7. The guide guards of the 18 rolling mills, and the guide guard beams were not assembled and aligned as required.
  8. The material shape of the 17 frame is not well matched with the imported guide plate.
  9. The splitting guide guard is not assembled as required, or the splitting wheel has the wrong eccentric direction or the direction is not uniform.
  10. The transfer of steel between the previous sorties, especially between the 12-13 racks.
  11. The torsion angle of the exit of the 17 aircraft was not adjusted properly.
  12. The rolling groove is severely worn.
  13. Splitting wheel and splitting guide and guard design issues.
  14. The gap of the connecting shaft is too large.

Solutions for 18 rack top exit failures

  1. Optimize the pass system and redistribute the reduction of each pass. Determine the production process.
  2. To explore the best technology, the focus is on heating parameters, the size of each rack, the speed and current parameters of each rack, and the formation standards are strictly implemented in each team.
  3. Improve the assembly level of the guide and guard of the rolling mill, and focus on the assembly of the guide and guard of the finishing rolling mill 15-16 to ensure the rigidity and axial stability of the rolling mill. Strictly do the pre-adjustment and installation of the guide and guard.
  4. Perform key cooling on the slitting belt.
  5. Improve the form of 18 guide guards and the size of the inner cavity, and control them within a certain range, so that the tip of the tongue is as close to the deformation zone as possible to improve the guidance.
  6. The material shape of the 17 rack and the installation of the imported guide plate should follow the following principles; when the hole pattern of the 17 rack is not full, the guide plate is not easy to deviate to cut the belt. When the 17 holes are full, the guide plate should be deflected in the opposite direction of the slitting belt.
  7. Check the roll wear in time.
  8. Change the form of guidance and guarding.
Article Categories:
Steel Making Technology
banner

Comments are closed.