FORD FLTM BB 114-1-2002 PROCEDURE FOR SEMI-GUIDED WRAP BEND FIXTURE FOR TESTING AND ANALYSIS OF THE BENDABILITY OF ALUMINUM SHEET.pdf

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1、 FORD LABORATORY TEST METHOD BB 114-01 Date Action Revisions 2002 12 06 Activated G. Luckey, P. Friedman, D. HoustonPrinted copies are uncontrolled Page 1 of 9 Copyright 2002, Ford Global Technologies, Inc. PROCEDURE FOR SEMI-GUIDED WRAP BEND FIXTURE FOR TESTING AND ANALYSIS OF THE BENDABILITY OF AL

2、UMINUM SHEET Application Scope This document covers the operation of a semi-guided wrap bend test fixture developed by Alcan International (Kingston Research and Development Centre in Ontario, Canada). The wrap bend fixture conforms to ASTM Standard E 290-97a and is used for the investigation of the

3、 bendability of various sheet aluminum alloys. Significance and Use This procedure describes the method for bend testing aluminum sheet with a semi-guided wrap bend test fixture and the analysis of test results. A standard bend test specimen of sheet is bent over the radius of a mandrel by a roller

4、rotating about the mandrel. The resulting convex surface of the bend is rated as a function of the amount of damage incurred due to bending about the mandrel. With acceptable bend rating defined, the minimum mandrel producing a successful bend is determined. The results are typically quantified in t

5、erms of the bend radius divided by the sheet thickness (r/t). Applicable materials This test applies to the bend testing of aluminum sheet with application in automotive stamping. Applicable Documents ASTM Standard E 290-97a Test Methods for the Bend Testing of Material for Ductility ISO 7438 Metall

6、ic Materials Bend Test Conflicts In the event of a conflict between the text of this manual and the references cited herein, the text of this manual shall take precedence. Definitions Orange Peel - A pebble-grained surface that develops in forming coarse-grained aluminum sheet. Orange peel roughenin

7、g is linked with the less constrained deformation of individual grains, with different orientations, at a free surface. It is related to grain size and is not noticeable on fine-grained material, since the individual crystals produce only extremely fine slip lines1. Quality Assurance Requirements Un

8、less otherwise specified, the users of this procedure are responsible for all inspection and the test requirements specified herein, and may use internal testing facilities as long as they meet the requirements of this procedure and any other test agencies acceptable to Ford Motor Company. FORD LABO

9、RATORY TEST METHOD BB 114-01 Page 2 of 9 Copyright 2002, Ford Global Technologies, Inc. Sampling Samples from a single production lot of alloy shall be used for the bendability evaluation of the alloy. The report for the bend test of the aluminum sheet shall contain as a minimum, the following infor

10、mation. (a) Generic and specific product description of each alloy including lot number and date alloy was made. (b) Baseline material properties for each aluminum alloy. (c) Material processing information. (d) Bend test ratings for each specimen tested. Replicates At least four replications per ma

11、ndrel are required for statistical significance. Data Reporting All physical and mechanical data shall be submitted using the Supplemental Data Reporting Package (SDRP), which is comprised of the form in the reporting section. The SDRP serves as the required reporting format for submitting material

12、data. All material data requested herein shall be manually recorded onto the reporting forms. Graphs and other requested materials shall be packaged and sent with the SDRP. Apparatus Required Semi-Guided Bend Test Fixture Alcan International developed the semi-guided wrap bend fixture (Figure 1a & 1

13、b) described within this document. The fixture was developed for bendability evaluation and quality control of aluminum sheet and conforms to ASTM Standard E 290-97a. The fixture clamps one end of an aluminum sheet specimen in place with the mandrel contacting the inside surface of the specimen at t

14、he location of the bend. The bending arm pivots about the radius of the mandrel and the roller applies the bending force against the opposite side of the specimen. The specimen is thus made to wrap around the mandrel producing a bend conforming to the mandrels radius. Maintenance The bend mandrels s

15、hould be cleaned with acetone periodically to remove oil and residue from bend test samples. Particular attention must be given to the radius of the mandrels. The mandrel radius must be kept clean, free of sold residue, and only aluminum is to be tested within the apparatus. Each mandrel bend radius

16、 must be inspected periodically to confirm the radius remains within testing tolerance. This inspection is to be conducted by the Metrology Lab of SRL. All threads, sliding blocks, and bearing must be kept clean and lightly lubricated. FORD LABORATORY TEST METHOD BB 114-01 Page 3 of 9 Copyright 2002

17、, Ford Global Technologies, Inc. Figure 1a. Guided wrap bend fixture schematic Figure 1b. Guided wrap bend fixture FORD LABORATORY TEST METHOD BB 114-01 Page 4 of 9 Copyright 2002, Ford Global Technologies, Inc. Test Specimen Dimensions The rectangular bend test specimens are to have length of 140mm

18、 +/- 0.5mm and a width of 25mm +/- 0.5mm. The orientation of the bend in relation to the roll direction of the sheet is to be identified. Longitudinal specimens are defined as having the length of the specimens parallel to the rolling direction (the bend line is perpendicular to the rolling directio

19、n). Transverse specimens are defined as having the length of the specimens perpendicular to the rolling direction (the bend line is parallel to the rolling direction). Prior to testing the samples should be cleaned with acetone to remove oils applied during cold rolling process of the sheet. Test Sp

20、ecimen Preparation Specimens may be fabricated with a shear or by electrical discharge machining (EDM). The shear may cause a small abrasive lip to form on the edge of the specimen that shall be filed down with medium grit sand paper for a smoother more uniform edge. Cracks observed within one thick

21、ness of the edge of the specimen are to be neglected in the bend surface rating analysis for both fabrication methods (shear or EDM). Number of Test Specimens It is recommended that no fewer than four (4) bend specimens per alloy be tested for each mandrel radius. Procedure Room Temperature: Room te

22、mperature shall be laboratory ambient conditions, which are assumed to be 23 C +/- 2C and 50 % +/- 10 % Relative Humidity. Exceptions should be noted and reported. Significant Figures: Unless otherwise indicated, all data shall be reported to three (3) significant figures. 1. All components necessar

23、y for the operation of the bend fixture are labeled in Figure 1a. 2. Ensure that the roller is moved back 6 to 13 mm away from the mandrel. 3. Choose an appropriate starting mandrel. 4. Adjust the end stop to the proper angle as designated on the mandrel (15 or 30 Degrees). To adjust, remove the det

24、ent pin and raise up or down accordingly. Re-insert detent pin. 5. Insert mandrel into slots provided, ensuring that it is seated (bottomed out) on the locating rod and that no fines are on the locating rod. 6. Clamp the mandrel in place by turning the mandrel tightening nuts finger tight on both th

25、e front and the back of the apparatus. 7. Insert a specimen using alignment pins protruding from clamp face. Clamp to verify that the correct spacer for clamping is in place so maximum available travel of clamping cam lever is achieved. FORD LABORATORY TEST METHOD BB 114-01 Page 5 of 9 Copyright 200

26、2, Ford Global Technologies, Inc. 8. If the spacer requires changing: a. Swing the bending handle against the end stop. b. Move the clamping block compression lever to access the spacer block. c. Remove the spacer block while still holding the lever. d. Insert the appropriate spacer block and releas

27、e. e. Swing the bending handle back. 9. Rotate the clamping cam lever on the left side of the apparatus to hold the specimen in place. 10. Check the clamping to ensure that there is no movement of the specimen. 11. Advance the roller adjustment nut in the center of the bending handle, until contact

28、with the specimen is made. DO NOT OVER TIGHTEN. Then back off 2 divisions (divisions scored on face of roller adjustment nut). 12. Tighten the roller adjustment lock nut to hold the roller into place. 13. Swing the bending handle around, from left to right as shown in Figures 2a-c. The complete wrap

29、 bend motion of the fixture (Figures 2a-c) should be completed in 2 seconds. Figure 2a. Semi-guided wrap bend fixture with bend specimen in place FORD LABORATORY TEST METHOD BB 114-01 Page 6 of 9 Copyright 2002, Ford Global Technologies, Inc. Figure 2b. Semi-guided wrap bend fixture in mid-travel of

30、 bend test Figure 2c. Semi-guided wrap bend fixture in final position of bend test 14. Return the bending handle to its original position (Figure 2a). DO NOT RELEASE THE CLAMPING CAM LEVER BEFORE SWINGING THE BENDING HANDLE BACK FROM RIGHT TO LEFT TO PREVENT THE ROLLER FROM CRASHING ON TOP OF THE CL

31、AMP. 15. Release the specimen using the clamping cam lever and identify the radius on it. FORD LABORATORY TEST METHOD BB 114-01 Page 7 of 9 Copyright 2002, Ford Global Technologies, Inc. 16. Insert a new sample. 17. To repeat with the same mandrel and material follow instruction from 9. 18. To chang

32、e mandrels, follow instruction from 2. 19. To use the same mandrel but with a different thickness of material, back off the roller and repeat from 6. 20. When finished with the apparatus, retract the roller fully back to avoid any accidents (i.e. roller banging top of the clamp face). 21. Each time

33、the mandrel needs to be changed, the roller MUST be moved out of the way. Analysis Semi-Guided Bend Test Rating Standard Bend surface damage such as orange peel, cracking, and full fracture are rated according to severity on a scale from 1-6. Any cracks within one thickness of the edge of the specim

34、en are not considered in the rating process. 1 No cracking, although mild to moderate orange peel is acceptable. 2 No cracking, but heavy orange peel is acceptable. 3 Crack initiation lines (i.e. lines of localized thinning or crazing) parallel to the bend line or cracks visible only with 3X magnifi

35、cation. 4 Discontinuous cracks visible with naked eye. 5 Continuous crack along entire bend line. 6 Fracture through bend thickness (i.e. light passes through the crack). *Examples of each bend rating are available in SRL laboratory 2144B. Within a population (greater than or equal to 4) of bend sam

36、ples of same bend radius, the average rating within the population shall be determined. The mandrel associated with an average rating equal to 2.4 is to be identified as the minimum bend radius for use in determining the minimum r/t (bend radius/sheet thickness) for the alloy. Limitations in the res

37、olution of the bend fixture may not identify the exact radius providing the average rating of 2.4. Interpolation may be used to determine the mandrels between which the average minimum bend radius exists. An example for determining the minimum r/t with interpolation is provided. FORD LABORATORY TEST

38、 METHOD BB 114-01 Page 8 of 9 Copyright 2002, Ford Global Technologies, Inc. EXAMPLE The mandrels between which the average sample rating is 2.4 is determined with the bend fixture to be 0.4064 mm and 0.3556 mm for an alloy sheet with a thickness of 0.9 mm. Mandrel radius Average Bend Sample Rating

39、0.4064 mm 2.0 0.3556 mm 3.2 Linearly interpolate between the mandrel radii to determine the radius corresponding to a 2.4 average rating. mmRadiusmmmmmmratingRadius3895.0)4.2()3556.04064.0(0.22.34.22.33556.0)(=+=Determine the minimum r/t by dividing the radius by the sheet thickness 4328.09.03895.0/

40、min=mmmmtrimumThe minimum r/t producing an acceptable bend surface is determined to be 0.4328 for the alloy. Incorporating interpolation into the method of bendability analysis offers improved resolution in testing with the semi-guided bend fixture. With bend fixture data, factors such as alloy chem

41、istry, heat treatments, pre-strain, etc. may be evaluated for their effect on bendability. Reporting 1. Complete identification of the material(s) tested, including alloy, manufacturer, lot / coil number, production data, gauge, and test date. 2. Complete identification of specimen fabrication metho

42、d, pre-strain, and treatments performed on test specimens. 3. The individual wrap bend rating of each specimen are to be recorded noting any unique or out of the ordinary observances. Each specimen should be marked for independent identification for future examination. 4. The average semi-guided wra

43、p bend test rating for each mandrel. 5. The minimum r/t providing an average rating of 2.4 for alloy. FORD LABORATORY TEST METHOD BB 114-01 Page 9 of 9 Copyright 2002, Ford Global Technologies, Inc. Supplemental Data Reporting Package (SDRP) References 1Altenpohl, D.G., Aluminum: Technology, Applica

44、tion, and Environment, The Aluminum Association and The Minerals, Metals, and Material Society, pp. 438, 1998 ID# Manuf: 4 samples:5.5 in x 1 in Lot/Coil: Orient.:Long. (bend line perpendicular to RD) Recd date: Trans. (bend line parallel to RD) Tes t date: Gauge: Specimen Orientation Bend Radii, in

45、 Test 1 Test 2 Test 3 Test 4 Test 5 Average Rating Interpolatedr/t(2.4) The rating guidelines are as follows: 1 - No cracking, although mild to moderate orange peel is acceptable 2 No cracking, but heavy orange peel is acceptable Notes: 3 Crack initiation lines (i.e. lines of localized thinning or crazing) parallel to the bend line or small cracks visible only with 3X magnification. 4 Discontinuous cracks visible with the naked eye. 5 - Continuous crack along entire bend line. 6 Fracture through bend thickness (i.e. light passes through the crack).