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Forming of AHSS using Servo-Presses

Groseclose, Adam Richard
http://rave.ohiolink.edu/etdc/view?acc_num=osu1408548321

Abstract Details

2014, Doctor of Philosophy, Ohio State University, Industrial and Systems Engineering.
Stamping of Advanced High Strength Steel (AHSS) alloys poses several challenges due to the material’s higher strength and low formability compared to conventional steels and other problems such as (a) inconsistency of incoming material properties, (b) ductile fracture during forming, (c) higher contact pressure and temperature rise during forming, (d) higher die wear leading to reduced tool life, (e) higher forming load/press capacity, and (f) large springback leading to dimensional inaccuracy in the formed part. [Palaniswamy et. al., 2007] The use of AHSS has been increasing steadily in automotive stamping. New AHSS alloys (TRIP, TWIP) may replace some of the Hot Stamping applications. Stamping of AHSS alloys, especially higher strength materials, 780 MPa and higher, present new challenges in obtaining good part definition (corner and fillet radii), formability (fracture and resulting scrap) and in reducing springback. Servo-drive presses, having the capability to have infinitely variable and adjustable ram speed and dwell at BDC, offer a potential improvement in quality, part definition, and springback reduction especially when the infinitely adjustable slide motion is used in combination with a CNC hydraulic cushion. Thus, it is desirable to establish a scientific/ engineering basis for improving the stamping conditions in forming AHSS using a servo-drive press. The overall objectives of the study are to determine the optimum slide velocity and forming conditions in stamping of selected AHSS (DP600, DP780, DP980 and DP1200) sheet materials in a servo press. The specific outcomes include: 1. Material property: material properties results (flow stress, yield, ultimate tensile, elongation, anisotropy) for selected AHSS alloy (DP590, CP800, DP980, TWIP900, TWIP980, and TRIP1180). 2. Lubrication condition: identified the best lubricants for forming DP590 and DP980 with the cup draw test. Determined the maximum value of coefficient of friction (COF) for forming these alloys. 3. Design guideline: identified guidelines for designing and forming stampings for AHSS alloys, i.e. corner radii, maximum thinning, draw depth, blank holder force, and ram velocity. 4. Ram velocity (servo-press): developed a methodology to optimize the ram velocity (velocity-stroke curves) and blank holder force in stamping AHSS alloy sheets in a servo press.
Jerald Brevick, Ph.D. (Advisor)
Taylan Altan, Ph.D. (Advisor)
Rajiv Shivpuri, Ph.D. (Committee Member)
157 p.
Industrial Engineering; Mechanical Engineering
Advanced High Strength Steel; AHSS; Servo Press; Sheet Metal Forming

Recommended Citations

Citations

  • Groseclose, A. R. (2014). Forming of AHSS using Servo-Presses [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1408548321

    APA Style (7th edition)

  • Groseclose, Adam. Forming of AHSS using Servo-Presses. 2014. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1408548321.

    MLA Style (8th edition)

  • Groseclose, Adam. "Forming of AHSS using Servo-Presses." Doctoral dissertation, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1408548321

    Chicago Manual of Style (17th edition)

osu1408548321
729
© 2014, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.