Page 50 - MetalForming-Nov-2018-issue

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MetalForming/November 2018
www.metalformingmagazine.com
LSP FloaterCoater
• Stainlesssteelconstruction
• Selectivearealubrication,top
and bottom
• Fastrollerchangeover
• Patentedsystemallowsroller to move with the stock
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Concast steel, with its lower produc- tion costs and improved internal quality and more consistent properties, took over from ingot casting. In Japan, the free-world’s leading producer at the time, nearly all steel was continuously cast, a fact at least partially responsible for the belief that Japan produced better steel than the United States. The domes- tic steel industry was undergoing sig- nificant restructuring at the time, closing many plants and laying off hundreds of thousands of workers. Nearly every U.S.-based steelmaker took on equity investments and/or entered into joint ventures with Japanese steelmakers, allowing for both a cash influx and tech- nology transfer. The Japanese steelmak- ers avoided limits
on exports and
gained a foothold
in the United
States at a time
when transplant
automakers were
growing and
wanted to buy the
same steels as available in their home country.
Hot-mill modifications introduced in the 1980s allowed for controlled- cooling thermal profiles that led to new higher-strength hot-rolled products with enhanced formability. Vacuum degassing units were installed at many steelmakers, enabling the production of steels with greater formability, which were demanded by the automotive industry. This, combined with the abil- ity to roll thinner and wider, a charac- teristic associated with continuous casting, gave users a greater selection of products from which to choose.
The late 1980s saw the first use of aluminum alloys in exposed automo- tive applications, with AA6111 and AA6016 recently commercialized. Development continued, leading to the creation of AA6016A and AA6022 in 1995, and AA6451 a decade later. These represent the workhorse grades
from the stamping process. Unfortu- nately, only upon a lengthy evalua- tion occurring after the purchase ofalotoftest equipment was it determined that
too many variables existed to consis- tently draw the same conclusion under supposedly identical test conditions. The LDH test is better suited for lubri- cant evaluations, where it continues to be used today.
Forming simulation, so critical now in saving significant time and money during part development, was essen- tially nonexistent in 1988. Established yield criteria could not accurately com- prehend anisotropic forming behavior. Nonlinear finite-element analysis was possible, but excessive computing time on workstations limited its routine use. Thirty years later, you can run simula- tions on your PC. Simulation-as-a-ser- vice business models exist today, allow- ing you to upload CAD files and receive results a short time later. Current pro- grams accurately predict thinning, stresses and strains, and metal flow for many different sheetmetals and form- ing processes. MF
The Science of Forming
companies that had dominated the industry for decades.
for high-quality stamped sheets in use today.
Panels and Press Shops
Although noncontact quality-con- trol tools are in routine use in many press shops today, the 1980s offered fewer options. Computing power, an expensive proposition back then, required extensive floor space. And what was programmed into comput- ers? Machine control software was understood only by a select few.
Any tool considered relatively fast and easy to use was looked upon as providing indispensable information. The Limiting-Dome-Height (LDH) LDH test was used in stamping plants 30 years ago to determine if a split part resulted from sheetmetal properties or
“Forming simulation, so critical now in saving significant time and money during part development, was essentially nonexistent in 1988.”