1、 FORD LABORATORY TEST METHOD BB 114-02 Date Action Revisions Rev. 1 2014 06 27 Revised See Summary of Revisions C. Mracna, NA 2013 11 20 Released C. Mracna, NA Controlled document at www.MATS Copyright 2014, Ford Global Technologies, LLC Page 1 of 6 PROCEDURE FOR SEMI-GUIDED WRAP BEND FIXTURE FOR TE
2、STING AND ANALYSIS OF THE BENDABILITY OF ALUMINUM SHEET Application 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
3、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. Bend rating and maximum acceptable r/t (radius / sheet thickness) shall be prescribed in the material specification. This test procedure shal
4、l be used to identify the maximum mandrel producing the prescribed bend rating. Results are quantified in terms of the bend radius divided by the sheet thickness and shall be denoted as r/t(prescribed rating #). Apparatus and Materials Required Semi-Guided Bend Test Fixture Alcan International devel
5、oped the semi-guided wrap bend fixture (Figure 1a & 1b) described within this document. The fixture was developed for bendability evaluation and quality control of aluminum sheet and conforms to ASTM Standard E290-97a. The fixture clamps one end of an aluminum sheet specimen in place with the mandre
6、l contacting the inside surface of the specimen at the 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
7、the mandrels radius. Mandrel Radii All bendability testing shall use the following bend mandrel radii: (in) (mm) 0.090 2.29 0.080 2.03 0.070 1.78 0.060 1.52 0.050 1.27 0.040 1.02 0.032 0.813 0.028 0.711 0.024 0.610 0.020 0.508 0.018 0.457 0.016 0.406 0.014 0.356 0.012 0.305 0.010 0.254 0.008 0.203 0
8、.006 0.152 0.004 0.102 0.002 0.051 FORD LABORATORY TEST METHOD BB 114-02 Copyright 2014, Ford Global Technologies, LLC Page 2of 6 Figure 1a - Guided wrap bend fixture schematic Figure 1b - Guided wrap bend fixture FORD LABORATORY TEST METHOD BB 114-02 Copyright 2014, Ford Global Technologies, LLC Pa
9、ge 3of 6 Maintenance The bend mandrels should 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 solid residue, and only aluminum is to be tested withi
10、n the apparatus. Each mandrel bend radius must be inspected at least annually to confirm the radius is within tolerance specified on mandrel engineering drawings. All threads, sliding blocks, and bearing must be kept clean and lightly lubricated. Test Specimen Dimensions The rectangular bend test sp
11、ecimens are to have length of 150 0.5 mm and a width of 25 0.5 mm. 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 perpendicula
12、r to the rolling direction). 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). Inspect samples prior to testing to confirm they are reasonably free of debris (i.e. sliver, chips, etc.) t
13、hat could influence bend test results. Test Specimen Preparation Specimens may be fabricated with a shear, mill, water jet, or by electrical discharge machining (EDM). Cracks observed within one thickness of the edge of the specimen are to be neglected in the bend surface rating analysis for both fa
14、brication methods (shear or EDM). Number of Test Specimens No fewer than ten (10) bend specimens per alloy shall be tested for each mandrel radius. Procedure 1. All components necessary for the operation of the bend fixture are labeled in Figure 1a. 2. Ensure that the roller is moved back 6 to 13 mm
15、 away from the mandrel. 3. Choose an appropriate starting mandrel. 4. Adjust the end stop to 30 degrees, unless otherwise specified in the material specification. To adjust, remove the detent pin and raise up or down accordingly. Re-insert detent pin. Note the use of alternative end stop angles (15
16、or 45 degrees) in reporting. 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 the front and the back of the apparat
17、us. 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. 8. If the spacer requires changing: a. Swing the bending handle against the end stop. b. Move the
18、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 release. e. Swing the bending handle back. 9. Rotate the clamping cam lever on the left side of the apparatus to hold the specimen in plac
19、e. 10. Check the clamping to ensure that there is no movement of the specimen. FORD LABORATORY TEST METHOD BB 114-02 Copyright 2014, Ford Global Technologies, LLC Page 4of 6 11. Advance the roller adjustment nut in the center of the bending handle, until contact with the specimen is made. DO NOT OVE
20、R TIGHTEN. Then back off 2 divisions (divisions scored on face of roller adjustment nut) or 0.008 inches (0.203 mm). The roller displacement is 0.004 inches (0.102 mm) per division. 12. Tighten the roller adjustment lock nut to hold the roller into place. 13. Swing the bending handle around, from le
21、ft to right as shown in Figures 2a-c. The complete wrap 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 Figure 2b - Semi-guided wrap bend fixture in mid-travel of bend test FORD LABORATORY TEST METHOD B
22、B 114-02 Copyright 2014, Ford Global Technologies, LLC Page 5of 6 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 L
23、EFT TO PREVENT THE ROLLER FROM CRASHING ON TOP OF THE CLAMP. 15. Release the specimen using the clamping cam lever and identify the radius on it. Review mandrel for burrs and fines, and clean with acetone if necessary. 16. Insert a new sample. 17. To repeat with the same mandrel and material follow
24、instruction from 9. 18. To change 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
25、 the clamp face). 21. Each time the mandrel needs to be changed, the roller MUST be moved out of the way. Evaluation 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 of 0-6. Any cracks within one thic
26、kness of the edge of the specimen (i.e. edge cracks that propagate less than one metal thickness from the edge) are not considered in the rating process. 0 No cracking & no orange peel* 1 No cracking, but has orange peel* 2 Crack initiation lines (i.e. lines of localized thinning or crazing) paralle
27、l to the bend line 3 Cracks visible to the naked eye and continuous crack length is less than 50% of bend sample width 4 Cracks visible to the naked eye and continuous crack length is greater than 50% of bend sample width, but less than the entire width of the coupon 5 Continuous crack along the ent
28、ire bend sample width 6 Complete fracture through bend thickness (i.e. sample splits/fractures into 2 pieces) * Orange peel is a pebble-grained surface that develops in forming coarse-grained aluminum sheet. Orange peel roughening is linked with the less constrained deformation of individual grains,
29、 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 linesi. FORD LABORATORY TEST METHOD BB 114-02 Copyright 2014, Ford Global Technologies, LLC Page 6of 6 Calculati
30、ng r/t Identify the maximum bend radius for which at least 5 of 10 bend samples have at least the prescribed bend rating defined in the material specification. Calculate r/t(prescribed rating #) by dividing this bend radius by the material thickness. Example Bend tests for three mandrels are reporte
31、d in the table below for a sheet material with a thickness of 3.0 mm. Mandrel Radius Rating per sample (in) (mm) 1 2 3 4 5 6 7 8 9 10 0.040 1.02 4 3 4 5 3 3 4 4 5 3 0.032 0.813 4 5 6 4 4 5 5 4 4 5 0.024 0.610 5 6 5 5 6 5 5 5 6 5 The material specification prescribes that r/t be established using a b
32、end rating of 5. The largest mandrel radius for which 5 or more samples have a rating greater than or equal to 5 radius is the 0.032 inches (0.813 mm) radius. The r/t(5) shall be calculated: 3.0 mm = 0.118 in 0.032 in 0.118 in = 0.271 The r/t(5) is 0.271. Reporting 1. Complete identification of the
33、material(s) tested including alloy, manufacturer, lot / coil number, CASH date, relevant production data, thickness, as-received temper, and as-received (lot release) mechanical properties. 2. Complete identification of all relevant bend sample processing information including, but not limited to, s
34、pecimen fabrication method, rolling direction orientation, pre-strain, heat treatment recipe, heat treatment date, as-tested temper, as-tested mechanical properties, and bend test date. 3. The individual wrap bend rating of each specimen shall be recorded noting any unique or out of the ordinary obs
35、ervances. Each specimen should be marked for independent identification for future examination. 4. Calculate r/t(#) and compare to maximum acceptable r/t(#) prescribed in the material specification. Summary of Revisions 2014 06 27 Expanded the evaluation rating scale from 0-5 to 0-6 to provide further resolution between 3-4 ratings. i Altenpohl, D.G., Aluminum: Technology, Application, and Environment, The Aluminum Association and The Minerals, Metals, and Material Society, pp. 438, 1998
