Academic literature on the topic 'Spiral corrugation'

"Length of Corrugation Land Cutting Back edge edge 1 0 --(a) (b) (c) FIGURE 8 Roll corrugations: (a) the cutting effect between rolls as a result of corrugations spiral; (b) action between corrugated rolls (S:S); (c) roll cross section showing the shape of corrugation. fast-moving roll scrapes the endosperm from the bran. As mills, it is possible to grind the material fed to the rolls in a the bran flakes get smaller toward the final breaking stages less severe manner. Roll surfaces should be maintained in and the endosperm layer attached to it becomes thinner, good condition to ensure good flour extraction and quality. gradually smaller corrugations are used (or a larger num-Depending on the quality of the steel and the type of ber of corrugations per inch of roll surface). Optimally milling technology used, corrugated rolls should be refur-conditioned wheat and the right corrugations, pressure, bished every 3-6 months of milling Other factors that in-and differential minimize splitting of the bran to particles fluence the need for refurbishing are roll surface alloca-of a size that can be sieved through with the flour. Good re-tion, feed rate per unit, severity of grinding, wheat sults in conventional milling are obtained when most of hardness, and presence of stones or other impurities in the endosperm free bran consists of large flakes. wheat. Recent advances in metallurgy that allow casting of The commercial flow should be designed to meet the re-harder outer surfaces for corrugated rolls extend the time quired capacity, wheat quality, and end products, and it is between refurbishing up to 8 months. based on specific machine surface values as shown in Even when the mix in the mill is changed drastically in Table 3 [56]. For example, the roll unit in the United States wheat size and kernels are smaller or larger than normal, allocates 0.3 inch of roll length per 100 pounds (cwt) of usually mills will continue using the existing corrugations, flour milled per 24 hours. Mills that use the metric system keeping many exiting variables unaltered. Generally, the would express the same roll units as 12.58 mm/100 kg gap between the rolls will be adjusted intuitively by the wheat/24 h. Conventionally with a longer break system, up miller based on his or her experience. A few studies were to six stages in hard wheat and seven in durum wheat conducted to evaluate the first roll action and the different TABLE 3 Mill Technical Specifications for Major Equipment for Different Kinds of Wheats' Wheat Hard Soft Durum Roll unit (mm) 10-15 10-13 16-20 Sifter surface (m 2) 0.055-0.081 0.083-0.088 0.086-0.093 Purifier width (mm) 3-70-38-12 aPer 100 kg processed wheat in 24 hours. Ref. 56." In Handbook of Cereal Science and Technology, Revised and Expanded. CRC Press, 2000. http://dx.doi.org/10.1201/9781420027228-7.