Roll defects

The two-drum winder is often called the work-horse among the winders on account of its easy set-up combined with high productivity and efficiency and its initial investment cost being lower than with the single-drum winder. The classical two-drum winder is an economic solution but its technological hmitation is the uncontrollable nip loads that necessarily occur when the roll diameters get above nip-load critical limits, with the consequent risk of roll defects. To overcome this drawback and to achieve low-intensity controlled nip pressures various modifications have been developed. 

The deformation of the covers in the nip especially at the first, i. e. wrapped drum , avoids roll defects such as corrugations and rope marks and allows winding of defect-free roUs with a larger diameter (Fig. 8.7). 

Sheet and Strip. The manufacture of wrought copper materials starts with either semicontinuously cast slabs that are hot roUed, or cast plate that is thin enough, near 13 mm (0.5 in.), to be cold roUed directly. The surfaces of both hot roUed slabs and as-cast plate are milled to remove defects before proceeding to cold rolling and annealing operations. 

Seams. As defects, seams are distinct from weld seams and may be found in nonwelded (seamless) tubes. They are caused by crevices that have been closed by some rolling process but remain unfused. 

Seams. As a defect, a seam is distinct from the seam resulting from a welding process. Seam defects can be found in nonwelded (seamless) tubes. They can originate from blow holes or nonmetallic inclusions in the ingot and are caused by crevices that have been closed by some rolling process but remain unfused. At times, they will appear in a spiral pattern in tubes. Seams can be very tight and appear as hairlines on the surface. They can cause failure when the component is pressurized. 

No other evidence of deterioration, such as corrosion, was apparent on either surface. The cracks are probably material defects. They may be laps or seams that were present on the external surface prior to the fin-rolling operation and were exaggerated during the rolling process. 

Intrinsic Steei Quaiity refers to the metallurgical and chemical properties of steel products (plate, pipe, tubes, structurals, castings, forgings) supplied to the fabricator for conversion into process equipment. Factors related to deoxidation, controlled finishing temperatures in rolling, and cleaning up of surface defects are included. 

Metallurgical deoxidation, rolling, damage, inadequate croppage of ends defects form notches or planes of internal, directional weakness. 

Use fully killed or fine grain steel, controlled rolling temperatures high Mn/C ratios eliminate sharp corners in design, remove defects from steel heat treat steel. For cryogenic operations use high nickel alloy steels or austenitic stainless steels, depending on temperature. 

Figure 4. Comparison of SRO-kinetics of Ag-23at%Zn for different states of defect atmealing. ( ) as-rolled state A (21% and 65% thickness reduction) (A), (0) isochronal defect annealing to 553K (state C) and 843K (state D), respectively, (A), 3h recrystallization treatment at 843K (state E). For more details see .

Electric motors may incorporate either sleeve or rolling-element bearings. A narrowband window should be established to monitor both the normal rotational and defect frequencies associated with the type of bearing used for each application. 

Rolling-element bearings The ability to monitor rolling-element or anti-friction bearing defects requires the inclusion of multiples of their rotating frequency. For example, with ball-pass inner-race bearings, the bandwidth should include the second harmonic (2x). 

Rolling-element bearing defect frequencies are the same as their rotational frequencies, except for the BSF. If there is a defect on the inner race, the BPFl amplitude increases because the balls or rollers contact the defect as they rotate around the bearing. The BPFO is excited by defects in the outer race. 

When one or more of the balls or rollers have a defect such as a spall (i.e., a missing chip of material), the defect impacts both the inner and outer race each time one revolution of the rolling element is made. Therefore, the defect vibration frequency is visible at two times (2x) the BSF rather than at its fundamental (lx) frequency. 

Platinum, palladium and the normal alloys of platinum used in industry are easily workable by the normal techniques of spinning, drawing, rolling, etc. To present a chemically clean surface of platinum and its alloys after fabrication, they may be pickled in hot concentrated hydrochloric acid to remove traces of iron and other contaminants —this is important for certain catalytic and high-temperature applications. In rolling or drawing thin sections of platinum, care must be taken to ensure that no dirt or other particles are worked into the metal, as these may later be chemically or elec-trolytically removed, leaving defects in the platinum. 

A number of cold-rolled alloys based on aluminium, copper and zinc are susceptible in varying degrees to recrystallisation on exposure to heat. This can have a detrimental effect on the adhesion of paint films. While there may, at first, be no sign of trouble, the defect will become obvious by brittleness of the film after some storage time has elapsed. 

In the experiments of pure rolling cases, Guangteng [51], Ehret [52], Felix [53] reported that the surface feature of a defect deformed prior to entering the high-pressure region... 

In Felix s experiments conducted on the surfaces prepared with arrayed defects and in lubricated contact [54], the dependence of deformation on the slide-to-roll ratio was also observed, but in a more complex mode, as presented in Fig. 24. In pure rolling, the defects deform and entrap lubricant underneath during their passage through the inlet zone. For the same reason as discussed above in single defect case, the... 

The amount of exogenous drug is difficult to determine. Before conducting release experiments, loaded halloysite was always washed with a large amount of water during a 5 minute rinse to ensure removal of material from the surface. However, we cannot exclude some of the active agent being attached to the outer surface of the halloysite, especially in the natural gap-defects on the cylinder surface at the end of the rolled clay sheet (it is a natural pocket on the tubule surface). The typical 5-10 % initial release burst we observed may be related to dissolution of this material. 

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