1、Designation: A971/A971M 17Standard Test Method forMeasuring Edge Taper and Crown of Flat-Rolled ElectricalSteel Coils1This standard is issued under the fixed designation A971/A971M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, t
2、he year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method provides a procedure for measuringedge taper and crown of flat-rolled electrical steel coi
3、ls asproduced at the steel mill.1.2 The values and equations stated in customary (cgs-emuand inch-pound) units or SI units are to be regarded separatelyas standard. Within this standard, the SI units are shown inbrackets. The values stated in each system may not be exactequivalents; therefore, each
4、system shall be used independentlyof the other. Combining values from the two systems mayresult in nonconformance with this standard.1.3 The following material specifications include require-ments for edge taper or crown: A677, A683, A726, A876, andA1086. Specification A840 also includes requirement
5、s for edgetaper or crown, but it has been withdrawn and reference to it isincluded for historical purposes.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety,
6、health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of Inte
7、rnational Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A340 Terminology of Symbols and Definitions Relating toMagnetic TestingA677 Specification for Nonoriented Electrical Steel Ful
8、lyProcessed TypesA683 Specification for Nonoriented Electrical Steel, Semi-processed TypesA726 Specification for Cold-Rolled Magnetic LaminationQuality Steel, Semiprocessed TypesA840 Specification for Fully Processed Magnetic Lamina-tion Steel (Withdrawn 2011)3A876 Specification for Flat-Rolled, Gra
9、in-Oriented, Silicon-Iron, Electrical Steel, Fully Processed TypesA1086 Specification for Thin-Gauge Nonoriented ElectricalSteel Fully Processed Types3. Terminology3.1 Definitions: Except as defined as follows, the symbolsand terminology used in this test method are defined inTerminology A340.3.1.1
10、edge taper and crownthe variations of thicknessacross the widths of cold-rolled steel coils, that is, perpendicu-lar to the rolling direction. Edge taper and crown are not thesame as thickness variation. Thickness variation is measuredparallel to the rolling direction (although it is loosely defined
11、 asvariation in any direction). See Fig. 1.3.1.1.1 crownthe variation of thickness from the edge tothe center, perpendicular to the rolling direction.3.1.1.2 edge taperthe variation of thickness from the edgeto approximately 4 in. 100 mm from the edge of the coil.3.1.1.3 edge taper gamma ()the slope
12、 of the edge taper (adimensionless number) expressed in ten thousandths of a unitper unit.3.1.2 edge trimmingthe slitting of a narrow strip fromeach edge of the master coil for discard. This reduces the edgetaper gamma on the remainder of the coil.3.1.3 gamma stripa 1 to 4 in. 25 to 102 mm strip cut
13、across the full width of the master coil (or master coil coupon),for the purpose of measuring edge taper and crown.3.1.4 master coilsfull-width coils as produced by cold-rolling mills. Slit coils are narrower width coils slit from a1This test method is under the jurisdiction of ASTM Committee A06 on
14、Magnetic Properties and is the direct responsibility of Subcommittee A06.01 on TestMethods.Current edition approved Oct. 1, 2017. Published November 2017. Originallyapproved in 1997. Last previous edition approved in 2010 as A971/A971M 10.DOI: 10.1520/A0971_A0971M-17.2For referenced ASTM standards,
15、visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright
16、 ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International
17、Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1Mon Apr 30 35 master coil. A master coil coupon is a full-width piece of themaster coil, usually manually cut off for test purposes.4. Summary of Test Method4.1 In determining th
18、e edge taper and crown, a gamma stripis taken from the coil head and tail. Thickness readings aretaken using a micrometer or other measuring device along asingle line perpendicular to the rolling direction at points38,138,238, and 438 in. 10, 35, 60, and 111 mm from each edgeto determine edge taper
19、and in the center to determine crown.The readings are recorded, and variations between the readingscalculated. If the edge taper is greater than specified, edgetrimming can be performed to meet the limits agreed uponbetween the producer and the user.5. Significance and Use5.1 Flat-rolled electrical
20、steel master coils are usually slitinto narrower coils. Usually these slit coils are punched orsheared into laminations of various shapes. The laminations arethen uniformly stacked to become the cores of magneticdevices such as motors and transformers. Stacking of manylaminations exhibiting excessiv
21、e taper causes assembly prob-lems and poor appearance. Nonuniform stack lengths in motorscause imbalance and noise. When the laminations are inter-leaved in transformers, taper causes air spaces within the coreresulting in increased noise, increased exciting current, andhigher core loss.6. Interfere
22、nce6.1 This test method assumes that edge taper and crown areconsistent through each individual coil. If different coils arewelded together to make up a finished coil, this may not be thecase. Nevertheless, edge trim can be used to correct forinconsistencies.7. Description of Gamma Strip and Equipme
23、nt Required7.1 A coupon is cut from head and tail ends of the mastercoil.Ashear in good working condition with sufficient capacityis used to cut a gamma strip from the coupon. The shear can befitted with an edge guide or other means to establish a stripperpendicular to the coil edges. Perpendiculari
24、ty shall bewithin 1. See Fig. 2.7.2 Means for locating and marking the gamma strip mea-surement points shall be provided.Atemplate can be made thatwill quickly locate for marking the test points from each edge.The center point can be located with a scale. Points shall belocated to within 0.032 in. 0
25、.81 mm. See Fig. 3.Alternatively,a machine may be constructed that automatically locates allnine points on the gamma strip, measures the points, andrecords/displays the data. If a continuous sequence of measure-ments are taken over the length of the strip (thickness profile),then the specified nine
26、points shall be read from the recordeddata.7.3 A micrometer or other thickness measuring device shallbe provided. The micrometer shall have anvils that are convexFIG. 1 Typical Steel Mill Coil Thickness Profile across Width of CoilFIG. 2 Typical Gamma StripA971/A971M 172Mon Apr 30 35 with a radius n
27、o less than 0.062 in. 1.6 mm. Operation maybe manual or automatic as part of a system of fixtures, gagingdevices, and data acquisition instruments. Thickness measure-ment device repeatability shall be 100 in. 2.54 m (onprecision gage block).NOTE 1Roughness of the steel sheet surface can affect repea
28、tability.7.4 A data sheet or computer printout shall be provided forentry of thickness readings and computation of gamma for thegamma strip.8. Procedure8.1 Measure and record the data for all nine points previ-ously specified.9. Calculation9.1 Calculate edge taper gamma as follows: 5XW2 Y!W104(1)whe
29、re: (gamma) = edge taper gamma,Xw= thickness at distance W from Y, in in. mm,andY = thickness at38 in. 10 mm from the edge, inin. mm.Thickness is measured at width increments W of 1.00, 2.00,and 4.00 in. 25.4, 50.8, and 102 mm from a point, Y,38 in. 10mm from the edge. These points are labeled X1, X
30、2, and X4,respectively.9.2 Calculate crown as follows (see Fig. 4):crown 5 XC2 Y (2)where:Y = average of the thicknesses38 in. 10 mm from eachedge, in in. mm andXc= thickness at center, in in. mm.The crown is measured at the center of the gamma strip andis substantially the thickest point across its
31、 width. Crown ismeasured the same way as edge taper except the distance Wcisbetween measurement points Xcand Y.9.3 Calculate edge taper as follows (see Fig. 4):edge taper 5 X42 Y (3)where:X4= thickness at 438 in. 110 mm from the edge, in in.mm, andY = thickness at38 in. 10 mm from the edge, in in. m
32、m.10. Interpretation of Results10.1 Edge taper gamma exceeding agreed upon limits canusually be corrected by edge trimming an amount sufficient tobring the coil into specification. Each edge of the coil shall beconsidered separately for the amount of trim. After trimming,this same method can again b
33、e followed.11. Precision and Bias11.1 This test method, although being followed by severalsteel mills and their customers, has not yet been the subject ofa comparison of the same samples at several laboratories(round robin). However, a computerized instrument that ad-heres to this test method has be
34、en in use in at least threelaboratories and supplier laboratories. At the time of prepara-tion of this test method, correlation has been achieved betweenthree such instruments to 0.0002-in. 5-m tolerance forNOTE 1Measurement points for opposite edge of gamma strip are the mirror image of the edge sh
35、own.FIG. 3 Measurement Points Marked on Gamma StripFIG. 4 Edge Taper/Crown DimensionsA971/A971M 173Mon Apr 30 35 several samples of steel coils. However, no statement ofprecision and bias is made at this time.12. Keywords12.1 coupon; crown; edge taper; edge trim; gamma strip;master coil; slit coilAS
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