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2、 STANDARD ENGINEERING DRAWING AND RELATED DOCUMENTATION PRACTICES Mathematical Definition of Dimensioning and Tolerancing Principles ASME Y14.5.1M-1994 The American Society of Mechanical Engineers 345 East 47th Street,New York,N.Y.1001 7-Copyrighted material licensed to Stanford University by Thomso
3、n Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.Date of Issuance:January 31,1995 This Standard will be revised when the Society approves the issuance of a new edition.There will be no addenda or writt
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9、accordance with governing ASME procedures and policies which preclude the issuance of interpretations by individual volunteers.No part o f this document may be reproduced in any form,in an electronic retrieval system or otherwise,without the prior written permission of the publisher.Copyright 0 1995
10、 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Resewed Printed in U.S.A Copyrighted material licensed to Stanford University by Thomson Scientific(),downloaded on Oct-05-2010 by Stanford University User.No further reproduction or distribution is permitted.Uncontrolled when printed.(This
11、 Foreword is not a part of ASME Y14.5.1M-1994.)The Y14 Committee created the Y14.5.1 Subcommittee in response to a need identified during a National Science Foundation (NSF)workshop.The International Workshop on Me-chanical Tolerancing was held in Orlando,Florida,in late 1988.The workshop report str
12、ongly identified a need for a mathematical definition for the current tolerancing standards.Tom Charlton coined the phrase “mathematization of tolerances.”The phrase meant to add mathe-matical rigor to the Y 14.5M standard.The response is the present standard,ASME Y 14.5.1M-1994.This new standard cr
13、eates explicit definitions for use in such areas as Computer Aided Design (CAD)and Computer Aided Manufacturing (CAM).The Committee has met three times a year since their first meeting af January of 1989 in Long Boat Key,Florida.Initial discussions covered scope of the document,boundary definitions,
14、size,and datums.The Committee identified four major divisions of a tolerance:1)the mathematical definition of the tolerance zone;2)the mathematical definition of conformance to the tolerance;3)the mathematical definition of the actual value;4)the mathematical definition of the measured value.The Sub
15、committee later decided that the measured value was beyond the scope of this Standard.When this Standard defines part conformance,it consists of the infinite set of points that make up all the surfaces of the part,and it is addressing imperfect form semantics.This Standard does not fully address the
16、 issue of boundary,that is where one surface stops and the other surface starts.The Subcommittee hopes to define this in the next edition of this Standard.The definition of size took up many days of discussions and interaction with the Y14.5 Subcommittee.It always came back to the statement of a micrometer-type two point cross-sectional measurement.The difficulty comes from the method of defining the cross-section.Consider a figure such as an imperfectly formed cylinder.When considering the infi
