Selected articles from September 2002 issue published on TheFabricator.com:
A new type of hydroforming press was recently developed for sheet applications. The new press incorporates data acquisition and control features for research purposes. Current press frame designs for tube and sheet forming are uneconomic for large forces. This press achieves a clamping force of 100 mN, which is absorbed by a single cast frame with a circumferential pretensioning system.
Switching from an oil-based lubricant to a water-based gel lubricant helped an exhaust-system components manufacturer, Zeuna Starker, reduce costs and cycle time. After studying several types of lubricants, the company chose a water-based gel that was less prone to spilling onto the floor and did not produce smoke during the welding process. The company reaped benefits in decreased housekeeping and disposal costs, and found that it did not need to wash the lubricant residue from semifinished parts before welding.
As tubular hydroforming becomes a competitive process for the mass production of automotive parts, a tube's material properties must be consistent. To predict variations in material properties, many tube producers use the uniaxial tensile test. Because the specimens for the tensile test are collected before a tube is bent and welded, they are not always accurate. To predict variations in tube property accurately, it should be tested under a biaxial state of stress.
Comparing and correlating two tests, a common bench test (twist compression) and a straight-tube corner-fill test, simulate hydroforming to find the coefficient of friction.
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