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Roll Pass Design

 
Quality Discussion

We provide a full range of roll pass consulting, with examples described in the following sections.

The value in a roll pass design program exists primarily in the accuracy of the process models integrated with it. In the sense of modern online software, it is also a great feature to have learning capability. In addition, a roll pass design program with minimal simplifications (e.g. in interstand tension) is also needed. Roll pass software with above-mentioned features should be capable of detecting weaknesses of existing roll pass schedules, and to modify existing pass schedules to create new ones. A poor roll pass design program relies on the designer's knowledge and experience; it only serves as a calculation program to do the things that even the Microsoft Excel can do. In comparison, a high-quality roll pass program hides complicity inside simple user interface and provides rich intelligence and knowledge, so that users without good design experience can still create great roll pass schedules.

From highly technological perspective, a high-quality roll pass schedule is mainly reflected in the accurate prediction of both metal deformation and force/power requirements, among others.

(1) Metal deformation, especially spread and forward slip. This affects overfill and underfill and speed. Overfill causes product shape defects, and underfill lowers down mill productivity and equipment utilization, because more passes may be needed, and grooves and rolls are not fully utilized. The most difficult portion of the exit speed calculation is the forward slip prediction. Accuracy in speed prediction is significant in continuous rolling and is most critical in the high-speed rolling block rolling. If the speed prediction is with too much negative error, then in the region between the current stand and the stand after, the steel would be loose and there is a tendency for metal accumulation. This could cause an accident if too many steel are accumulated. For high-speed mill (e.g. rolling block, or No-Twist Mill NTM) this would be a critical trigger for flutter (mill vibration) and consequent noise. With the trigger for the vibration, many other factors could magnify the scale of the vibration and cause flutter. Flutter may cause the mill hard or impossible to operate. This problem happened in quite a few wire rod mills in USA in the late 90s. During continuous rolling, volume flow per unit time in every stand should be a constant. Therefore, not only the speed, but also the cross-section area has effects on the volume constancy. Prediction error in cross-section area is mainly affected by the calculation error of spread.

(2) Force and power requirements. Positive error in the force prediction leads to either high amount of investment waste or mill utilization waste with positive error, while negative error results in high potential for equipment damage. For a mill supplier, force error would translate into a higher equipment construction cost and sale price. A known mill builder which had about 30% force prediction error sold mills at almost twice as high price as its key competitor. Though it claimed that its mill had higher quality, in fact, most portion of the price difference was considered to be due to its wrong estimate in equipment strength (stand, transmission system and motor, etc.), so it built mill too much stronger than needed!
 

Metal Pass Resources on Roll Pass  (Ask a question)

Examples of Metal Pass resources available for roll pass consulting are as follows:


Metal Pass has dozens of research reports and some software applications available at no charge for the Metal Pass Consulting clients.

 

Please contact us via email admin@metalpass.com or by phone (001) 503 516 9625 for top quality consulting services.
 

 
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