128_1-p2 - Sliver Generation Reduction in Trimming of...

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Ming Li Mem. ASME Alcoa Technical Center, Alcoa, Inc. Alcoa Center, PA 15069 Sliver Generation Reduction in Trimming of Aluminum Autobody Sheet Aluminum autobody sheets produce appreciable amounts of slivers during trimming op- erations when trimmed with dies conventionally designed for steel sheets. The slivers can be carried through downstream processes and cause damage to the surface of formed parts resulting in costly manual repair. This paper reports a systematic experimental study at both the macro- and micro-scale of the sliver generation problem with relation to cutting angle, clearance, and blade sharpness. It is concluded that slivers can be reduced or even eliminated by modifying the current trimming tools designed for steel sheets. The most striking finding is that the conventional wisdom of 0-degree cutting conditions gen- erate the largest amount of slivers for aluminum alloy sheets. With proper cutting angles, trimming aluminum autobody sheets can actually be more robust than that for steel sheets—the clearances can be less restrictive and tools may require much less frequent sharpening. The microscopic investigation traced the origins of slivers and revealed the mechanisms of sliver generation. The paper demonstrates that the integration of material microstructure and mechanics is very beneficial for solving a significant manufacturing problem and can greatly improve the process of shearing aluminum alloy autobody sheet. @ DOI: 10.1115/1.1540113 # 1 Introduction Recent years have seen a rapid increase in the use of aluminum alloys in automotive components due to the requirement for fuel efficiency and high performance. Aluminum alloys are the natural choice over steel for light-weighting, corrosion resistance, and easy-recycling. However, aluminum alloys as ‘‘new’’ materials to the automotive industry pose many challenges to manufacturing processes that have traditionally dealt with steels. One such challenge occurs in the process of press forming ~ termed ‘‘stamping’’ ! of aluminum alloy sheet material into body panels ~ e.g., hoods, doors, fenders, etc. ! . A typical manufacturing flow path of the press forming process consists of stretch/draw, trim & pierce, flange/pre-hem, and final hem. Subsequently, the panels go to assembly. The problem is, aluminum alloy sheets produce appreciable amounts of slivers during trimming opera- tions when trimmed with dies conventionally designed for steel sheets. Sliver is the general term of debris and small aluminum pieces produced in the trimming operation. It was found in this work that slivers can generally be categorized morphologically into three types, fine and hair-like sliver, needle-like sliver, and flake/particle. Figure 1 is an optical micrograph of a piece of hair-like sliver from a production line.
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  • Fall '15
  • Aluminium, Blade, sliver generation

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