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1、J IS JAPANESE I NDUSTR IAL STANDARD Translated and Published by Ja pa nese Standards Association JIS H 7702 :2*3 Method for springback evaluation in stretch bending of aluminium alloy sheets for automotive use ICs 43.040.60; 77.040.10; 77.150.10 Reference number : JIS H 7702 : 2003 (E) PROTECTED BY
2、COPYRIGHT 7s Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 23:02:42 MDTNo reproduction or networking permitted without license from IHS -,-,- H 7702 : 2003 Foreword This translation has b
3、een made based on the original Japanese Industrial Standard established by the Minister of Economy, Trade and Industry through deliberations at the Japanese Industrial Standards Committee in accordance with the Industrial Standardization Law. Attention is drawn to the possibility that some parts of
4、this Standard may conflict with a patent right, application for a patent after opening to the public, utility model right or application for registration of utility model after opening to the public which have technical properties. The relevant Minister and the Japanese Industrial Standards Committe
5、e are not responsible for identifying the patent right, application for a patent after opening to the public, utility model right or application for registration of utility model after opening to the public which have the said technical properties. Date of Establishment: 2003-10-20 Date of Public No
6、tice in Official Gazette: 2003-10-20 Investigated by: Japanese Industrial Standards Committee Standards Board Technical Committee on Non-Ferrous Metals JIS H 7702 : 2003, First English edition published in 2004-03 Translated and published by: Japanese Standards Association 4-1-24, Akasaka, Minato-ku
7、, Tokyo, 107-8440 JAPAN In the event of any doubts arising as to the contents, the original TIS is to be the final authority. O JSA 2004 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, i
8、ncluding photocopying and microfilm, without permission in writing from the publisher. Printed in Japan PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 23:02:42 MDTNo
9、 reproduction or networking permitted without license from IHS -,-,- H 7702 : 2003 Contents Page Scope 1 Normative references 1 Definitions 1 Principle 1 Test equipment 2 Test piece 2 Test 2 Report 3 Annex 1 (normative) Calculation method of surface pressure acting on test piece 5 Annex 2 (normative
10、) Calculation method of tension . 7 Annex 3 (normative) Measuring method of curvature radius by dial gauge 8 PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 23:02:42
11、MDTNo reproduction or networking permitted without license from IHS -,-,- JAPANESE INDUSTRIAL, STANDARD JIS H 7702 : 2003 Method for springback evaluation in stretch bending of aluminium alloy sheets for automotive use 1 Scope evaluation in stretch bending of aluminium alloy sheets for automotive us
12、e. This Japanese Industrial Standard specifies the method for springback 2 Normative references The following standards contain provisions which, through reference in this Standard, constitute provisions of this Standard. The most recent editions of the standards (including amendments) indicated bel
13、ow shall be applied. JIS G 0202 Glossary of terms used in iron and steel (testing) JIS Z 2248 Method of bend test for metallic materials JIS Z 8401 Guide to the rounding of numbers 3 Definitions For the purposes of this Standard, the definitions given in JIS G O202 and the following definitions appl
14、y. a) quantity of springback That is the quantity calculated according to the following formula (i) from the curvature radius at the time of loading and after unloading as shown in Attached Fig. 1. (1) I i/.& - i/rh I Ir:, - r, I r-2 . - - 77= yrin where, 77 : quantity of springback ri, : curvature
15、radius at the time of loading (mm) rin : curvature radius after unloading (mm) stretch bending That is the method for bending of test piece by adding ten- sion in processing or at the proper time. curvature radius That is the value corresponding to the radius at top end of punch in the pressing bend
16、 method specified in JIS Z 2248, and means the cur- vature radius, ri, and &, of inside surface of test piece at the time of loading and after unloading as shown in Attached Fig. 1. surface pressure That is the value of the force loading to the direction of thickness of test piece in order to give t
17、ension divided by the apparent area of the loaded test piece. The calculation method is as shown in Annex 1. tension That is the force per unit cross section area acting on the right-angled direction to the bending axis of test piece by the load of surface pressure and the bending deformation. The c
18、alculation method is as shown in Annex 2. b) c) d) e) 4 Principle This method is to add tension to a test piece, to give a bending de- formation until it reaches the specified radius and to measure the quantity of springback from the change of curvature radius of test piece at the time of loading an
19、d after unloading. PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 23:02:42 MDTNo reproduction or networking permitted without license from IHS -,-,- 2 H 7702 : 2003
20、5 Test equipment The test equipment shall be as follows. a) Stretch bending tester for evaluation of springback quantity The ex- ample of stretch bending tester to be used for test shall be as shown in Attached Fig. 2. For the radius of punch, 100 mm shall be made the standard. However, the radius o
21、f punch may be decided according to the agreement between the parties concerned with delivery. Measuring instrument for curvature radius For the measurement of cur- vature radius of test piece, a dial gauge of 0.001 mm in minimum scale shall be used. The measuring method of curvature radius by dial
22、gauge is as shown in Annex 3. b) 6 Test piece The test piece to be used for test shall be as follows. a) The test piece shall be rectangular of 500 mm in length and 50 mm in width. b) The thickness shall be the original thickness of the material as it is. c) The cutting-off direction of test piece s
23、hall be parallel and right-angled to the rolling direction. The cross section of test piece shall be as it is cut. In the case of especially specified or in the case of other method than cutting, the unnecessary deforma- tion or heating to the part to be the test piece shall be avoided. The surface
24、of the test piece shall be free from detrimental defects to influence the results such as scratch. d) e) 7 Test The test shall be as follows. a) Test temperature The test temperature shall be within the range between 10 O C and 35 OC, and if required, the test temperature shall be recorded. Espe- ci
25、ally, when the temperature control is required, the test temperature shall be 23 “C f 5 O C . Stretch bending The test piece shall be fixed with pressing plate and dies (see Attached Fig. 21, and a surface pressure(1) shall be added. The punch shall be pressed up and moved up to the height, h, to be
26、come the condition in which the winding angle of test piece and punch exceeds 120“ in angle. The quantity of punch pressed-in h(2), and the lubricant to be used for test shall be decided according to the agreement between the parties concerned with delivery. The quantity of punch pressed-in h, shall
27、 be measured by using of a deflection meter and the punching force P, shall be measured by using a load cell. The press-in speed and unloading speed of punch shall be decided according to the agree- ment between the parties concerned with delivery. Notes (1) The surface pressure shall be in the rang
28、e from O MPa to 5.0 MPa, and four or five conditions shall be provided within this range. (2) For the exceeding of 120“ of winding angle, the quantity of punch pressed-in shall be not less than 70 % of radius of punch. Calculation of tension The tension shall be calculated according to Annex 2. b) c
29、) PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 23:02:42 MDTNo reproduction or networking permitted without license from IHS -,-,- 3 H 7702 : 2003 d) Measurement of
30、 curvature radius and calculation of springback quan- tity The curvature radius, rln, of test piece after unloading shall be measured by using the measuring instrument of curvature radius 5 b) according to the method as shown in Annex 3. The curvature radius, ri, at the time of loading shall be the
31、radius of top end of punch. The quantity of springback, q, shall be calculated according to formula (1). The test results shall be rounded-off to two decimal places according to JIS Z 8401. 8 Report The items of report shall be subjected to the agreement between the parties concerned with delivery,
32、and selected from the following items. a Normative references b) Test piece number c) Test condition, radius of punch, quantity of punch pressed-in h, lubricant, punching force, surface pressure Result, tension, quantity of springback q d) e) Classification of material i) At the time of loading 2) A
33、fter unloading a) Curvature radius at b) Curvature radius after the time of loading, ri, unloading, i-:, Attached Fig. 1 Curvature radius at the time of loading and after unloading PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Empl
34、oyees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 23:02:42 MDTNo reproduction or networking permitted without license from IHS -,-,- 4 H 7702 : 2003 Unit: mm a) Outline of tester Unit : Upper plate of die Die Pressing plate Punch (R100) Lower plate of die mm set set b) Tool Attached Fig
35、. 2 Stretch bending tester for evaluation of springback quantity (example) PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 23:02:42 MDTNo reproduction or networking p
36、ermitted without license from IHS -,-,- 5 H 7702 : 2003 Annex 1 (normative) Calculation method of surface pressure acting on test piece The surface pressure acting on test piece shall be calculated by using the follow- ing formula (1) and formula (2) (see Annex 1 Fig. i). (1) Axps p = S S=50X 250- x
37、 2 = 50 x (500 - wd) (2) i 2) where, p : surface pressure acting on test piece (MPa) A : pressurized area of hydraulic cylinder (mm2) ps : measured value of hydraulic pressure in hydrau- lic cylinder (MPa) S : apparent total area at pressurized part of plate pressing force of test piece (mm2) W d :
38、interval of pressing plate of tool (mm) Pressurized part of A II I II I Unit: mm ,- Test piece Annex 1 Fig. 1 Contact part of test piece to tool PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie
39、Not for Resale, 03/12/2007 23:02:42 MDTNo reproduction or networking permitted without license from IHS -,-,- 6 H 7702 : 2003 The example of dimensions of tool Attached Fig. 2 b) in the text is as shown in Annex 1 Fig. 2. Unit: mm , . - Test piece r - 7 Pressurized part of plate pressing force I Il
40、I I PartA Annex 1 Fig. 2 Dimensions of tool (example) PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 23:02:42 MDTNo reproduction or networking permitted without lice
41、nse from IHS -,-,- 7 H 7702 : 2003 Annex 2 (normative) Calculation method of tension The tension added to test piece shall be calculated by using of the following for- mula (i) and formula (2) (see Annex 2 Fig. i). . (1) P 2btsinO T = where, T : tension added to test piece (MPa) P : punch force (N)
42、b : width of test piece (mm) t : thickness of test piece (mm) 8 : angle formed by the direction of punch force and test piece (rad) Rd : radius of punch (mm) rd : radius of each part R of upper metallic mould (mm) Wd : interval of pressing plate of tool (mrn) h : quantity of punch pressed-in (mm) T
43、T P IL Annex 2 Fig. 1 Relation of punch load to tension PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 23:02:42 MDTNo reproduction or networking permitted without li
44、cense from IHS -,-,- 8. H 7702 : 2003 Annex 3 (normative) Measuring method of curvature radius by dial gauge 1 Dial gauge The outline of dial gauge is as shown in Annex 3 Fig. 1 a). 2 Measuring method When the curvature radius of test piece after unloading is rin, imagine the condition in which the
45、measuring instrument is contacted with it see Annex 3 Fig. 1 b). The point contacted with the stylus of dial gauge is regarded as A, the points contacted with the corner part of pedestal are regarded as B and C, the centre of curvature radius is regarded as O, and the intersecting point of seg- ment
46、 AO and BC is regarded as D. If the distance between the corner parts of ped- estal is put as w and the measured value by dial gauge (the length of AD) is put as x, the formula (i) is obtained because the equation, m2 = BD2 + m2, is formed in the triangle of BOD according to the theorem of three squ
47、ares. (1) . 2 &2 = - +(& -x) (3 The formula (2) is obtained by expanding to arrange formula (i), and the curva- ture radius, &, of test piece is obtained from the measured value, x, of dial gauge and formula (2). (2) . , x u12 Ti* = - + - 2 8x , , r Stylus of dial gauge I - I / I Insidesurface I i :
48、I ,/ ( oftest piece / Pedestal of O a) Outline of dial gauge b) Measuring method Annex 3 Fig. 1 Outline of dial gauge and measuring method PROTECTED BY COPYRIGHT Copyright Japanese Standards Association Provided by IHS under license with JSALicensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 03/12/2007 23:02:42 MDTNo reproduction or networking permitted without license from IHS -,-,- E r r a t a