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Forming and Fabricating Presses On

 Ellen Kehoe

 

 

 

 

 

 

By Ellen Kehoe
Senior Editor

The collective topics of forming and fabricating are a heavyweight segment of the SME Technical Paper library, with nearly 800 papers from 1951 to present. Here’s an overview of the many areas covered in the fabrication and material forming case studies and tutorials in SME’s database.

Forging, tube fabrication, extrusion and drawing are connected with more than 100 papers each. Other topics with high numbers of papers include stamping, blanking, hydroforming, explosive forming, thread forming, laser forming, shearing, slitting, presses and transfer die fabrication.

In recent years, forming and fabricating papers have come primarily from educational sessions at FABTECH and from NAMRI/SME’s annual North American Manufacturing Research Conference (NAMRC), representing, respectively, industry user best practices and state-of-the-art developments in fabricating novel materials for innovative applications.

 

Forging Ahead

Metalworking through forging is one of the oldest crafts, and many papers chronicle the transformation from traditional techniques to promising new methods to meet the challenges for metal components of all types. For example, pneumatic-mechanical high energy rate forging equipment made a dramatic difference for a company with no previous forging capability. Over 18 months with four pieces of equipment, the company successfully developed its full production requirement of rock bit cutters.

There was concern in the late 1950s whether it was delusional to evolve from the success of close-tolerance forgings for gas turbines and jet engine compressor blades and turbine buckets to precision forgings—“a different breed of cat”—for airframe parts. Conventional forging leaves plenty of “meat” on areas to be machined, while precision forging should be within finish dimension tolerances in almost all areas.

Environmental concerns regarding forging and diecasting lubricants arose in the 1970s as anti-pollution and workplace safety laws took effect. The long-standing satisfactory use of low-cost crude oil mixes in the forging process presented problems for water-based lubricant formulators. By the way, none other than the well-known S.C. Johnson & Son, Inc. (Racine, WI) slid in an early paper on metalworking lubricants, made of wax, of course.

 

Tube Fabrication

Hydroforming is mentioned prominently relative to tube and sheet fabrication. A 2005 review of the technology presented at FABTECH was coauthored by SME Fellow Taylan Altan of Ohio State University (Columbus, OH). The paper noted breakthroughs that reduce process development time and enable sheet and tube hydroforming processes to compete with traditional stamping. Warm hydroforming of tube and sheet was being investigated to increase the application of lightweight Mg and Al alloys that are difficult to form at room temperature.

Another paper coauthored by Professor Altan and presented at NAMRC describes lubrication mechanisms and their effect on interface friction in tube hydroforming. 01-1 Excessive thinning in tube bending may lead to tearing in bending or premature bursting in hydroforming. To compensate for the thinning, a boosting force is typically applied to one tube end, but boosting can cause wrinkling. NAMRC authors from the University of Michigan (Ann Arbor, MI) and Virginia Commonwealth University (Richmond, VA) develop a wrinkling indicator correlated with a finite element simulations of rotary draw tube bending.

Finite element model for rotary draw tube bending simulation (tube not shown), from SME Tech Paper TP07PUB47, H. Orban et al.

A rigid-plastic finite element method for the numerical analysis and design of a tube hydroforming process is described in a 2002 NAMRC paper by authors from Pusan National University (Korea). The process was applied to hydroforming processes for an automobile bumper rail, subframe and lower arm.


SME Technical Papers

More than 16,000 papers and presentations make SME’s collection of manufacturing knowledge the largest of its kind. Find papers on best practices, advancements and industry trends. Add your insights to help others Learn More & Do More.



Published Date : 12/10/2014

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