IX

Shape and yield improvement

No

Name

Description

Client / Employer

91

Decreasing hooking and camber with better shape control in the later passes with adjustments in roll bending and force distribution on passes.

Several C++ subroutines that calculated the work roll bending for each pass were used to achieve slightly long centers. The bending subroutines also calculated the adjustments of bending during the dynamic changes in the forces. The level 1 approach to dynamic adjustments of bending during the passes was reviewed and corrected for problems of gain or response. Code to ramp the roll bending in level 1 on the head and tail to avoid reaching the upper limit of the roll bending and maintain good shape was also provided. The ramping of the roll bending for thermal changes in the crown during the first 15 seconds of reversing passes was recommended. The centerline gage was often used to track the progress of the effect on the hook and camber. The operators were trained to learn to setup and adjust the steering better.

Bethlehem, OSM, Ipsco, Nanjing, SMC

92

Decrease edge wave and center wave with adjustment in force distribution and roll bending.

This work used the same tools and adjustments described above in item 91. There were edge and center wave measuring tools that could be used to provide feedback to operators and the level 1 and 2.

Bethlehem, OSM, Ipsco, Nanjing

93

Decreasing the turn down of the head on later passes that cause missed slots, kinks, knuckles or other defects.

Literature references on the effects of the differential speed between the top and bottom rolls were used to provide guidance on head end delta speeds. The percentage differences in speeds and the length of the sustained differences to avoid turn down were recommended. Both positive and negative differences, depending on the thickness and the reductions of the passes, were recommended. The tools to measure the turn down and ways to store and use the measurement to minimize the problem on specific products were recommended.

OSM, Nanjing, Allegheny Ludlum

94

Decreasing wave and bow by setting hot and cold leveler

Models for retained strain after roller leveling were used to set up the leveling. Gap settings to maximize flatness without exceeding the limits of leveler were recommended. The level 1 and level 2 software to perform the correct settings was tuned and adjusted.

Bethlehem, Nanjing

115

NISCO Plate Mill Head-End and Tail-End Quality Improvement

This project is to reduce NISCO plate mill head-end and tail-end cambers. When there is high error in the head-end or tail-end force prediction, the calculated initial roll gap will be inaccurate. AGC has to move in a big scope to adjust the roll gap. In this process, any weakness in the mill control and operation may trigger significant head-end and/or tail-end defects. Therefore, the first attempt would be the force model improvement in this aspect. In addition, based on the parameter variation in the head-end and tail-end, thickness gradients will be created in the two ends, in order to achieve the equal thickness throughout the length. NISCO's Level 1 system from Siemens doesn't have sufficient features for head-end and tail-end to coordinate with the Level 2, so both Level 1 and Level 2 should be improved.

Nanjing