A Hybrid Forming System: Electrical-Assisted Double Side Incremental Forming (EADSIF) Process for Enhanced Formability and Geometrical Flexibility

Cao, Jian ; Xia, Z. Cedric ; Gutowski, Timothy G. ; Roth, John

Northwestern University (Evanston, Ill.)

关键词: Machine Tools;    Business;    Casting;    Configuration;    Enhanced Formability;   

DOI  :  10.2172/1039329
RP-ID  :  DOE/EE/0003460
RP-ID  :  EE0003460
RP-ID  :  1039329

美国|英语

来源: UNT Digital Library

【 摘 要 】

The objectives of this project are to establish the scientific bases, engineering technologies and energy/emission impact of a novel dieless forming process, Double side Incremental Forming (DSIF), and to explore the effectiveness of its hybrid variation, Electrical-Assisted Double Side Incremental Forming (EADSIF), on increasing the formability of metallic sheets. The scope of this project includes: (1) the analysis of environmental performance of the proposed new process as compared to conventional sheet metal forming processes; (2) the experimental investigation of the process capabilities of DSIF and EADSIF via the self-designed and newly established lab-scale EADSIF equipment; (3) the development of the essential software in executing the new proposed process, i.e., the toolpath generation algorithms; and finally (4) the exploration of the electricity effect on material deformation. The major accomplishments, findings and conclusions obtained through this one and a half years exploratory project are: (1) The first industrial medium-size-scale DSIF machine using two hexapods, capable of handling a sheet area up to 675 mm x 675 mm, was successfully completed at Ford. (2) The lab-scale of the DSIF machine was designed, fabricated and assembled to form a workpiece up to 250 mm x 250 mm. (3) Parts with arbitrary freeform double-curvatures using the genetic, not geometric-specific tooling were successfully formed using both machines. (4) The methodology of the life cycle analysis of DSIF was developed and energy consumption was measured and compared to conventional forming processes. It was found that the DSIF process can achieve 40% to 90% saving when the number of parts produced is less than 50. Sensitivity analysis was performed and showed that even at very large number of produced parts (greater than 2000), incremental forming saves at least 5% of the energy used in conventional forming. (5) It was proposed to use the offset between the two universal tools in DSIF to actively create a squeezing effect on sheet metal and therefore, increase the geometric accuracy. The idea was confirmed through both experimental and numerical validations. (6) A novel toolpath strategy, i.e., the so-called In-to-out toolpath or accumulative toolpath, was proposed to further increase formability and geometric accuracy compared to the SPIF configuration. A dimensional form accuracy of 1 mm can be achieved using the new strategy. (7) The effect of electricity on magnesium alloy was experimentally investigated. It was found that the formability has a ridge with respect to the applied current density and pulse duration. This finding implies that there are multiple choices of process parameters that are workable depending on the desired microstructure. The above results demonstrated that DSIF/EADSIF is a promising forming technology that can create impacts in revolutionizing how the prototyping and small volume production of sheet metals will be fabricated, i.e., it can (1) eliminate the need of casting and machining of drawing dies; (2) tailor material utilization to function requirement therefore achieving a light weight product; (3) reduce the amount of sheet metal scraps; and (4) shorten the engineering and manufacturing time for sheet metal parts from the current 8 {approx} 25 weeks to less than 1 week after the technology is fully developed. DSIF/EADSIF can be implemented in aerospace, automotive and appliance industries, or be used for producing personalized and point-of-use products in medical industry. Our analysis has shown that once developed, verified and demonstrated, the implementation and growth of DSIF will increase U.S. manufacturing competitiveness, advance machine tool and software industries, and create opportunities for emerging clean energy and low-carbon economy with estimated energy savings of 11 TBtu and CO2 reduction of 1 million tons per year. The work has been disseminated into three (3) journal articles and two (2) provisional patent submissions. A new company has been spun off from this research group aiming to commercialize the technology. A team, consisted of Northwestern Kellogg Business school students and Northwestern McCormick Engineering school graduate students, has independently examined business facts and business models, and has assisted in developing go-to-market strategy. One of the key recommendations for utilizing the full potential of this work is to demonstrate the DSIF/EADSIF concept in a true large-scale industrial setup, i.e., being able to form sheet size of 1.5 m x 1.5 m, where technical challenges, such as machine design, shape compensation, dynamic effect on geometrical accuracy, need to be further explored.