Wear mechanisms in forming of HSS and AHSS

Code : C/64/09

Roll forming cryo-rolled nano-structured aluminium sheet

Commercial purity aluminium plate was reduced by rolling under nitrogen in 30 passes from an initial material thickness of 10 mm to a final thickness of 2 mm (80% reduction). Analysis of the microstructure showed that the material produced in this way had an ul-trafine grained microstructure. The sheet was roll formed at room temperature to a V-section using commercial roll forming equipment. Two sets of experiments were per-formed; one with a 15 mm radius in the base of the V and the other with a 5 mm radius. The performance in terms of final shape and springback is compared with the same part shape formed by V-die bending. The mechanical properties of the sheet were determined using the tensile test. It has been found that even if the total tensile elongation is close to zero and bending of the material is very limited, ultra-fine grained and low ductile sheet metals can be roll formed to simple section shapes.

Benchmark 3 : incremental sheet forming

 Benchmark-3 is designed to predict strains, punch load and deformed profile after spring-back during single tool incremental sheet forming. AA 7075-O material has been selected. A corn shape is formed to 45 mm depth with an angle of 45º. Problem description, material properties, and simulation reports with experimental data are summarized.

An audio signal based model for condition monitoring of sheet metal stamping process

Tool condition monitoring is an important factor in ensuring manufacturing efficiency and product quality. Audio signal based methods are a promising technique for condition monitoring. However, the influence of interfering signals and background noise has hindered the use of this technique in production sites. Blind signal separation (BSS) has the potential to solve this problem by recovering the signal of interest out of the observed mixtures, given that the knowledge about the BSS model is available. In this paper, we discuss the development of the BSS model for sheet metal stamping with a mechanical press system, so that the BSS techniques based on this model can be developed in future. This involves conducting a set of specially designed machine operations and developing a novel signal extraction technique. Also, the link between stamping process conditions and the extracted audio signal associated with stamping was successfully demonstrated by conducting a series of trials with different lubrication conditions and levels of tool wear.

Sheet Metal Examples

A wall in the Sheet Metal Department at the New York Trade School shows many examples of duct work, pipe, and decorative metal work that students learn to produce. Black and white photograph that is starting to fade.

Graduate of the Sheet Metal Department, Thomas Carlough

A 1946 graduate of the Sheet Metal Department, Thomas Carlough is pictured at work at the Triangle Sheet Metal Works, Inc. Original caption reads, "Thomas Carlough - Sheet Metal 1946. The Sheet Metal Draftsman lays out the duct work etc, for the ventilation and Air Conditioning of buildings." Black and white photograph with caption adhered to reverse.

Graduate of the Sheet Metal Department, John Loonie

John Loonie, a graduate of the Sheet Metal Department of the New York Trade School, is pictured welding at work in the Triangle Sheet Metal Works Inc. Original caption reads, "John Loonie - Sheet Metal 1955, one of the Sheet Metal workers employed at the Triangle Sheet Metal Works, qualified to weld." Black and white photograph with caption adhered to reverse.

Students in the Sheet Metal Department at Work

A view of students at work in a classroom in the Sheet Metal Department at the New York Trade School. Black and white photograph.

Graduate of the Sheet Metal Sheet Metal Department David Harning

David Harning graduated from the Sheet Metal Department in 1957 and is shown in his position as Sheet Metal Cutter at the Triangle Sheet Metal Works Inc. Original caption reads, "David Harning - Sheet Metal 1957, is shown at his bench where he lays out all types of Sheet Metal pieces. These pieces will be constructed by other Sheet Metal Workers." Black and white photograph with captioned adhered to reverse.

Surface modification by metal ion implantation forming metallic nanoparticles in insulating matrix.

There is special interest in the incorporation of metallic nanoparticles in a surrounding dielectric matrix for obtaining composites with desirable characteristics such as for surface plasmon resonance, which can be used in photonics and sensing, and controlled surface electrical conductivity. We investigated nanocomposites produced through metallic ion implantation in insulating substrate, where the implanted metal self-assembles into nanoparticles. During the implantation, the excess of metal atom concentration above the solubility limit leads to nucleation and growth of metal nanoparticles, driven by the temperature and temperature gradients within the implanted sample including the beam-induced thermal characteristics. The nanoparticles nucleate near the maximum of the implantation depth profile (projected range), that can be estimated by computer simulation using the TRIDYN. This is a Monte Carlo simulation program based on the TRIM (Transport and Range of Ions in Matter) code that takes into account compositional changes in the substrate due to two factors: previously implanted dopant atoms, and sputtering of the substrate surface. Our study suggests that the nanoparticles form a bidimentional array buried few nanometers below the substrate surface. More specifically we have studied Au/PMMA (polymethylmethacrylate), Pt/PMMA, Ti/alumina and Au/alumina systems. Transmission electron microscopy of the implanted samples showed the metallic nanoparticles formed in the insulating matrix. The nanocomposites were characterized by measuring the resistivity of the composite layer as function of the dose implanted. These experimental results were compared with a model based on percolation theory, in which electron transport through the composite is explained by conduction through a random resistor network formed by the metallic nanoparticles. Excellent agreement was found between the experimental results and the predictions of the theory. It was possible to conclude, in all cases, that the conductivity process is due only to percolation (when the conducting elements are in geometric contact) and that the contribution from tunneling conduction is negligible.