《ANSI-B74.21-1986-R2002.pdf》由会员分享，可在线阅读，更多相关《ANSI-B74.21-1986-R2002.pdf（36页珍藏版）》请在三一文库上搜索。
1、Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=IHS Employees/1111111001, User=Griebel, Gabriele Not for Resale, 05/10/2007 07:23:34 MDTNo reproduction or networking permitted without license from IHS -,-,- .-. . . _- ANSI 874.22 A b W 0724250 000342b
2、 5 I I American National Standards Institute An American National Standard implies a consensus of those substan- tially concerned with its scope and provisions. An American National Standard is intended as a guide to aid the manufacturer, the consumer, and the general public. The existence of an Ame
3、rican National Standard does not in any respect preclude anyone, whether he has approved the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standard. Amer- ican National Standards are subject to periodic review and users
4、are cautioned to obtain the latest editions. Producers of goods made in con- formity with an American National Standard are encouraged to state on their own responsibility in advertising, promotion material, or on tags or labels, that the goods are produced in conformity with particular American Nat
5、ional Standards. Published bg American National Standards Institute 1430 Broadway, New York, N. Y. 10018 Copyright 0 1986 by American National Standards Institute, Inc. No portion of this publication may be quoted or reproduced in any form without the zuritten permission of the Amer-ican National St
6、andards Iwtitute. PRINTED IN U.S.A. - Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=IHS Employees/1111111001, User=Griebel, Gabriele Not for Resale, 05/10/2007 07:23:34 MDTNo reproduction or networking permitted without license from IHS -,-,- A N S
7、I B 7 4 * 2 1 Bb 0724350 0003427 7 W American National Standard Fatigue Proof Test Procedure for Vitrified Grinding Wheels Sponsor Grinding Wheel Institute Approved January 9, 1986 American National Standards Institute ANSI B74.21-1986 Copyright American National Standards Institute Provided by IHS
8、under license with ANSI Licensee=IHS Employees/1111111001, User=Griebel, Gabriele Not for Resale, 05/10/2007 07:23:34 MDTNo reproduction or networking permitted without license from IHS -,-,- A N S I 874.23 86 m 0724350 0003428 7 m I F O R E W O R D (This Foreword is not a part of the American Natio
9、nal Standard Fatigue Proof Test Procedure for Vitrified Grinding Wheels, B74.21-1986) This standard was originally developed by the Safety Research Sub- committee of the Grinding Wheel Institute to provide a nationally recog- nized standard for the fatigue proof testing of vitrified grinding wheel s
10、pecifications. It is intended to serve as a common basis for fatigue testing of vitrified abrasive bodies. Work on this standard was initiated by the subcommittee in conjunc- tion with a laboratory at one of the nations leading universities and the results of preliminary investigations indicated tha
11、t the test was sufficiently meaningful to justify the development of a standard for the testing of fatigue properties of vitrified abrasive bodies. The draft was originally prepared in March of 1980. After a number of revisions and re-evaluations, it was submitted to Technical Committee No. 1 on Bon
12、ded Abrasives of ANSI Standards Committee B74 on June 19, 1984. The B74 Committee approved the document on December 5, 1985 and final approval was granted by the American National Standards Insti- tute on January 9, 1986. Standards are reviewed for reaffirmation or revision at least once in five yea
13、rs. Suggestions for improvement which may be developed through the use of this stand,ard are welcome and should be sent to the American National Standards Institute, 1430 Broadway, New York, NY 10018. Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=IH
14、S Employees/1111111001, User=Griebel, Gabriele Not for Resale, 05/10/2007 07:23:34 MDTNo reproduction or networking permitted without license from IHS -,-,- The Accredited Standards Committee on Abrasives, B74, which reviewed and approved this standard had the following personnel at the time of appr
15、oval. R. E. POOLES, Chairman A. P. WHERRY, Secretary Organization Represented Name of Representatve Abrasive Engineering Society . .JACK McAvo Abrasive Grain Association .DAVID R. NICHOLS American Institute of Chemical Engineers J, H. STERNE, III Cemented Carbide Producers Association JOE J. LEY A.
16、P. WHERRY (elk.) Coated Abrasives Manufacturers Institute . R. M. GAWREAU C. M. STOCKINGER (alt.) Compressed Air and Gas Institute, Pneumatic Tool Section. . ROBERT A. WILLOUGHBY J? H. ADDINGTON (alt.) Cutting Tool Manufacturers of America . CHARLES M. STOCKINGER Diamond Wheel Manufacturers Institut
17、e L. P. KUZMICK Grinding Wheel Institute .ROBERT E. POOLES Industrial Diamond Association af America, Inc. . RAYMOND A. UZANAS Metcut Research Associates, Inc. ALAN F. ACKENHAUSEN Power Tool Institute, Inc. .JOHN RUSHMER Society of Carbide and Tool Engineers . MAURY BRASSERT University of Massachuse
18、tts . .JOHN E. RITTER, JR. Society of Manufacturing Engineers . DAVID ASHPOLE, Technical Committee No. 1 on Bonded Abrasives . R. H. POOLES, Chuimn A. P. WHERRY (alt.) A. P. WHERRY (alt.) A. P. WHERRY (,alt.) BRUCE DUNNINGTON (alt.) DAVID J. AUBEL (alt.) JOSEPH B. FREILAND (alt.) Corresponding Membe
19、y L. P. KUZMICK RUSSELL MONJAR J. A. MACRAE J. L. MCAVOY Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=IHS Employees/1111111001, User=Griebel, Gabriele Not for Resale, 05/10/2007 07:23:34 MDTNo reproduction or networking permitted without license fr
20、om IHS -,-,- . . ! A N S I 874.23 Bb W 072LI350 0003LI30 7 a TABLE OF CONTENTS 1 . Purpose 1 2 . Background 1 3 . scope 1 4 . Application Guidelines . 1 5 . Overview of the Standard Procedure . 1 6 . Measurement of Fatigue Properties 2 7 . Calculations of Proof Spin Test Factor . 6 8 . Safety Factor
21、s in This Procedure 6 Appendices A . Calculation of Fatigue Constants N and B Using Median Stress Analysis . 8 B . Calculation of Fatigue Constants N and B Using Homologous Stress Analysis . 12 C . Determination of Strengbh Data Consistency . 16 D . Test Bar and Loading Details ; Strength Calculatio
22、n . 16 E . Thermal Stress Determination . 17 F . Example Calculation of Proof Spin Test Factor for Constant SFPM Operation . 20 G . Example Calculation of Proof Spin Test Factor for Constant RPM Operation 21 H . I . J . K . Setup for Bar Strength Tests . 22 Fatigue and Fluids Used for Testing and Gr
23、inding 24 Typical. Inadmissible. and Error-Prone Values of N and B 26 Glossary of Symbols and Terms . 28 Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=IHS Employees/1111111001, User=Griebel, Gabriele Not for Resale, 05/10/2007 07:23:34 MDTNo reprodu
24、ction or networking permitted without license from IHS -,-,- A N S I B 7 4 * 2 1 86 I 0724L50 000343L 7 B B j I I I 1 Fatigue Proof Test Procedure for Vitrified Grinding Wheels 1. Purpose The purpose of this Procedure is to outline a proof test method that will increase the degree of surety at which
25、 a vitrified grinding wheel will not fail from normal openating stresses due to fatigue during its useful lifetime. 2. Background It has become known that ceramic materials are susceptible to fatigue. Tests carried out under the sponsorship of the Grinding Wheel Institute (GWI) showed that ceramic b
26、onded (Le., vitrified) grinding wheel compositions also are susceptible to fatigue. The GWI immedi- ately made this information available to mem- ber companies and established a more extensive program for further research. It was found possible to define a working life at which a vitrified grinding
27、wheel should not fail from fatigue. An inter-relationship was found to exist among the applied stress in the wheel, the wheel proof test stress, and the rate of fatigue of the wheel composition. The original method for measuring the rate of fatigue of a grinding wheel composition in- volved a test s
28、panning many weeks. The GWI concluded that a short-term test was needed since each member company would need to de- termine the fatigue rate of many compositions. Tests were carried out from 1975 to 1982 to validate a procedure for rapid measurement of the fatigue rate of vitrified grinding wheel co
29、mpositions. Those tests were successful and this Procedure is based upon methods validated by them. 3. Scope The scope of this Procedure is limited to vitri- fied bonded compositions containing aluminum oxide or silicon carbide abrasive grains, when used in environments found in normal grinding prac
30、tice. This Procedure provides a tool to in- crease the degree of surety of these products against fatigue failure from normal operational stresses. 4. Application Guidelines 4.1 General. Some uses of grinding wheels do not result in fatigue becoming a significant fac- tor during the useful life of t
31、he wheel. The 1 fatigue phenomenon is characterized by the magnitude and duration of application of opera- tional stresses, and by the fluid and thermal environment to which the wheel is exposed. This Procedure may be used for individual wheel specifications used in specific applications. It may als
32、o be used to develop proof spin test factors for a broad line of product specifications. Thus, each user of this Procedure must decide which wheel specifications and applications should be subjected to this Procedure. The usage characteristics listed below will help to identify applications for high
33、 or low susceptibility to fatigue. But the user of the Procedure should bear in mind that there is an inter-relationship among these factors. 4.2 Known Factors That Increase Fatigue Susceptibility (a) Increasing operating speed, in SFPM. (b) Constant SFPM operation as contrasted to constant RPM oper
34、ation. (c) Increasing time of rotation prior to dis- card. (d) Increasing usage time that the wheels active face is substantially hotter than its bore. (e) Use of water-based coolant as contrasted to other grinding fluids. 4.3 Known Factors That Decrease Fatigue Susceptibility (a) Decreasing operati
35、ng speed. (b) Non-wheel applications, e.g., segments, honing stones, etc. (e) Wheels having effectively no hole, e.g., mounted points. (d) Short wheel life applications. (e) Dry grinding, wheel face cool. 5. Overview of the Standard Procedure 5.1 Measure the following fatigue properties of the vitri
36、fied wheel composition : Fatigue Rate Constant, N Fatigue Constant, B Inert Strength, Si Copyright American National Standards Institute Provided by IHS under license with ANSI Licensee=IHS Employees/1111111001, User=Griebel, Gabriele Not for Resale, 05/10/2007 07:23:34 MDTNo reproduction or network
37、ing permitted without license from IHS -,-,- ANSI B74-23 86 U 0724350 0003432 O E 5.2 Select a minimum lifetime (Tmin) based on product usage. 5.3 Calculate a proof spin test factor (STF) . 5.4 Proof test wheels using standard spin test equipment. 6. Measurement of Fatigue Properties 6.1 General. Th
38、is procedure applies to each vitrified material specification selected. 6.2 Test Samples. 6.2.1 Test Bar Dimensions: 6” min. length x 1.000 f 0.025” width x 0.500 f 0.025” thick- ness, flat and parallel within ,O1 inch. 6.2.2 Number of Test Bars Required. The number of bars manufactured shall be suf
39、ficient for: the number of loading rates selected (see 7 6.4.2.1) ; the number of bars selected per load- ing rate in grinding fluid (see r 6.4.2.2) ; this same number of bars for inert testing, e.g., in liquid nitrogen; and an allowance for possible scrap (see 7 6.2.3). 6.2.3 Test Bar Preparation M
40、ethods Recommended Method (most practical)-As- Molded Bars. A single mix is prepared and the bars uniformly spread and molded. The top sur- face of each bar as-molded is identified. Mold flash must be removed. The bars are dried and fired together. Each fired bar is numbered, weighed, and measured a
41、nd these data recorded. Density variation must not exceed the standard commercial tolerance for that specification. A minimum of 85% of all bars must meet dimen- sional and density requirements. If less than 85% survive, discard all of them and start again. Alternative A - Molded and Ground Bars. Us
42、e the same procedures as the Recommended Method except that each bar is molded oversize in one or more of its dimensions and the fired bar is finish ground to the required size, Alternative B-Bars Cut from Wheels. Large diameter wheels (e.g. 20 x $ 4 4 x 1) are manu- factured. The sides of the fired
43、 wheels are ground to reach the required bar thickness. Bars are then cut from the wheel to the re- quired width and length, 6.3 Testing Machine and Accessories. The test- ing machine shall load the test bars to fracture in the transverse bending mode, while continu- ously measuring the applied load
44、. It shall have the capability to load the bars at a minimum of three different loading rates, with a ratio of at least 1000 between the fastest and slowest rates. The crosshead rate must be measurable and controllable to within k 5%. The fastest rate shall not exceed the response capability of the
45、test machine or its recording instrument. The testing machine shall be equipped with a four-point loading fixture. This fixture shall consist of bearing blocks which insure that the forces applied to the bar are normal only and without eccentricity. Refer to American Society for Testing Materials do
46、cument C78, “Standard Method of Test for Flexural Strength of Con- crete.” See Appendix D in this Procedure for bar-loading geometry. The fixture shall be de- signed such that the test bar can be loaded while submerged in liquid, Appendix H illus- trates the setup for bar strength tests and de- tail
47、s of a coolant bath. 6.4 Test Procedure 6.4.1 General. The test bars shall be stressed to fracture in a four-point loading, transverse bending mode. Appendix D shows the loading geometry and the equation for breaking strength. The breaking strength of bars shall be determined in two environments, on
48、e inert and the other active. Inert tests shall be con- ducted with bars that have been immersed in liquid nitrogen (see 7 6.4.2.5). Active tests shall be conducted in a medium that simulates, or is more severe as to fatigue than the environment the wheel is exposed to in normal use. Infor- mation on the severity of various fluid environ- ments is presented in Appendix I. Paragraph 6.4.2.3 below describes a standardized, severe environment that is recommended for general testing for applications using water-based fluids. For dry grinding applications, bar tests may be conducted in a