1、Designation: A 971/A 971M 05Standard Test Method forMeasuring Edge Taper and Crown of Flat-Rolled ElectricalSteel Coils1This standard is issued under the fixed designation A 971/A 971M; the number immediately following the designation indicates the yearof original adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon (e) 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 stee
3、l coils 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,
4、each 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: A 677, A 683, A 726, A 840/A 840M, and A 876.1.4 This standard does not p
5、urport 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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2
6、A 340 Terminology of Symbols and Definitions Relating toMagnetic TestingA 677 Specification for Nonoriented Electrical Steel FullyProcessed TypesA 683 Specification for Nonoriented Electrical Steel, Semi-processed TypesA 726 Specification for Cold-Rolled Magnetic LaminationQuality Steel, Semiprocess
7、ed TypesA 840/A 840M Specification for Fully Processed MagneticLamination SteelA 876 Specification for Flat-Rolled, Grain-Oriented,Silicon-Iron, Electrical Steel, Fully Processed Types3. Terminology3.1 Definitions: Except as defined as follows, the symbolsand terminology used in this test method are
8、 defined inTerminology A 340.3.1.1 edge taper and crownthe variations of thicknessacross the widths of cold-rolled steel coils, that is, perpendicu-lar to the rolling direction. Edge taper slope (g) is expressed inten thousandths of an inch per inch (ten thousandths of amillimetre per millimetre).3.
9、1.1.1 DiscussionThe variation of thickness from theedge to approximately 4 in. 100 mm from the edge of the coilis called edge taper. The variation of thickness from the centerto the edge is called crown.3.1.1.2 DiscussionEdge taper and crown are not the sameas thickness variation. Thickness variatio
10、n is measured parallelto the rolling direction (although it is loosely defined asvariation in any direction).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 master coil.3.1.3 master coilsfull-wid
11、th coils as produced by cold-rolling mills. Slit coils are narrower width coils slit from amaster coil. A coupon is a full-width piece of the master coil,usually manually cut off for test purposes. A sample strip 1 to4 in. 25 to 102 mm wide is sheared across the width of thecoil from a coupon for th
12、e purpose of measuring edge taper andcrown. This is called a gamma strip because gamma (g)isthesymbol used to quantify edge taper slope or rate of variationwith distance. See Fig. 1.4. Summary of Test Method4.1 In determining the edge taper and crown, a samplegamma strip is taken from the coil head
13、and tail. Thicknessreadings are taken using a micrometer or other measuringdevice along a single line perpendicular to the rolling directionat points38 ,138 ,238 , and 438 in. 10, 35, 60, and 111 mmfrom each edge to determine edge taper and in the center todetermine crown. The readings are recorded,
14、 and variationsbetween the readings calculated. If the edge taper is greater1This test method is under the jurisdiction of ASTM Committee A06 onMagnetic Properties and is the direct responsibility of SubcommitteeA06.01 on TestMethods.Current edition approved Dec. 15, 2005. Published January 2006. Or
15、iginallyapproved in 1997. Last previous edition approved in 2000 as A 971 00.2For referenced ASTM standards, 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 ont
16、he ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.than specified, edge trimming can be performed to meet thelimits agreed upon between the producer and the purchaser.5. Significance and Use5.1 Flat-rolled electrical ste
17、el 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. Uniform stacking ofmany laminations exhibiting exc
18、essive taper causes assemblyproblems and poor appearance. Nonuniform stack lengths inmotors cause imbalance and noise. When the laminations areinterleaved in transformers, taper causes air spaces within thecore resulting in increased noise, exciting current, and coreloss.6. Interference6.1 This test
19、 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 correct for the worst case7. Description of Sample Gamma Strip and EquipmentRequired7.1 A coupo
20、n 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. Perpendicularity shall bewithin 1. S
21、ee 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. 0.81 mm. See Fig. 3.InF
22、ig. 3,CWis coil width, and CW/2 locates its center. Alternatively, amachine may be constructed that automatically locates all ninepoints on the gamma strip, measures the points, and records/displays the data. If a continuous sequence of measurementsare taken over the length of the strip (thickness p
23、rofile), thenthe specified nine points shall be read from the recorded trace.7.3 A micrometer or other thickness measuring device shallbe provided. The micrometer shall have anvils that are convexwith a radius no less than 0.062 in 1.6 mm. Operation may bemanual or automatic as part of a system of f
24、ixtures, 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 repeatability.7.4 A data sheet or computer printout shall be provided forentry of thickness rea
25、dings and computation of gamma for thegamma strip.FIG. 1 Typical Steel Mill Coil Thickness Profile across Width of CoilFIG. 2 Typical Gamma StripA 971/A 971M 0528. Procedure8.1 Measure and record the data for all nine points previ-ously specified.9. Calculation9.1 Edge taper and crown are defined as
26、 the thicknessvariation perpendicular to the rolling direction of the steel coilor sheet. Edge taper gamma is in ten thousandths of an inch perinch ten thousandths of a millimetre per millimetre of width.See Fig. 4.9.2 Calculate edge taper gamma as follows:g5XW Y! 104W,104in./in. (1)g5XW Y!104W,104m
27、m/mm (2)where:g (gamma) = units of edge taper,Xw= thickness at distance W from Y, andY = thickness at38 in. 10 mm from the edge.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, X2, an
28、d X4,respectively.9.3 Calculate crown as follows:crown 5 XC Y! 104,104in. 104mm# (3)where:Y = average of the thicknesses38 in. 10 mm from eachedge andXc= thickness at center.The crown is measured at the center of the gamma strip andis substantially the thickest point across its width, CW. Crownis me
29、asured the same way as edge taper except the distance Wcis between measurement points Xcand Y. Generally, crowncauses much smaller gamma values than edge taper.10. Interpretation of Results10.1 Edge taper gamma exceeding agreed upon limits canusually be corrected by edge trimming an amount sufficien
30、t tobring the master coil into specification. Each edge of the mastercoil shall be considered separately for the amount of trim.Aftertrimming, this same method can again be followed.11. Precision and Bias11.1 This test method, although being followed by severalsteel mills and their customers, has no
31、t 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 been in use in at least threelaboratories and supplier laboratories. At the time of prepara-tion of this test method, correlation h
32、as been achieved betweenthree such instruments to 0.0002-in. 5-m tolerance forseveral 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 coilNOTE 1Measurement points for opposite
33、 edge of gamma strip are the mirror image of the edge shown.FIG. 3 Measurement Points Marked on Gamma StripFIG. 4 Edge Taper/Crown DimensionsA 971/A 971M 053ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standar
34、d. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed
35、 every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible t
36、echnical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).A 971/A 971M 054
