Tooling-integrated sensing systems for stamping process monitoring

In-situ stamping process monitoring plays a critical role in enhancing productivity and ensuring part quality in sheet metal stamping. This paper investigates the realization of two sensing methods to create a tooling-integrated sensing system: mutual inductance-based displacement measurement for sheet draw-in, and distributed contact pressure measurement at the tool–workpiece interface. The two sensing systems are complementary in nature, and together, they significantly enhance the on-line observability of the stamping process. The performance of the draw-in sensor was evaluated using numerical simulations and experiments in a small-scale and a large-scale lab setup, and its effectiveness has been confirmed under the presence of wrinkled sheet. To study the spatial and temporal variations of the tool–workpiece contact pressure in a stamping operation, experiments were conducted on a customized panel stamping test-bed with an array of thin-film force sensors embedded below the die flange and die cavity. The force sensor data were then numerically interpolated to form the contact pressure distribution across the tool–workpiece interface, based on the thin plate spline (TPS) method. Comparison between the interpolated pressure obtained from the surface generation techniques and direct measurement using redundant sensors and a press mounted load cell confirms the validity of the new contact pressure sensing method. The integrated sensing technique provides insight into the stamping process by quantifying process variations and providing a reference base for process control to reduce product disparities. Additionally, new product and process designs can be created based on the quantified and referenced variations.     

Supplementation of the diet with the functional fiber PolyGlycoplex? is well tolerated by healthy subjects in a clinical trial

Background  

The relationship of dietary fiber to overall health is of great importance, as beneficial effects have been demonstrated with the use of fiber from diverse sources, some traditional, other novel. PolyGlycopleX^? (PGX^?) is a unique proprietary product composed of three water-soluble polysaccharides, that when processed using novel technology give rise to a final product – a soluble, highly viscous functional fiber.     

The safety of PolyGlycopleX? (PGX?) as shown in a 90-day rodent feeding study

Background  

This study was designed to evaluate the safety of PolyGlycopleX^? (PGX^?), a novel viscous dietary polysaccharide (fiber), when administered to Sprague Dawley^? rats in the diet for 90 days.     

Shape Selective Chemistries with Modified Mordenite Zeolites

This is a review of work carried at Dow Chemical on the design and characterization of novel mordenite catalysts with a unique micro and meso-porous structure characterized by a variety of methods including, TEM, BET surface area and pore size distribution, and n-decane hydro-conversion. The catalytic performance of these catalysts in shape selective reactions is illustrated with results from n-decane hydro-conversion and applications to alkylation and trans-alkylation reactions of mono and polynuclear aromatic hydrocarbons and other chemistries. Juan M. Garcés and G. John Lee both retired from The Dow Chemical Company.     

Lattice Strain Due to an Atomic Vacancy

Volumetric strain can be divided into two parts: strain due to bond distance change and strain due to vacancy sources and sinks. In this paper, efforts are focused on studying the atomic lattice strain due to a vacancy in an FCC metal lattice with molecular dynamics simulation (MDS). The result has been compared with that from a continuum mechanics method. It is shown that using a continuum mechanics approach yields constitutive results similar to the ones obtained based purely on molecular dynamics considerations.     

Chemical Interactions and Their Role in the Microphase Separation of Block Copolymer Thin Films

The thermodynamics of self-assembling systems are discussed in terms of the chemical interactions and the intermolecular forces between species. It is clear that there are both theoretical and practical limitations on the dimensions and the structural regularity of these systems. These considerations are made with reference to the microphase separation that occurs in block copolymer (BCP) systems. BCP systems self-assemble via a thermodynamic driven process where chemical dis-affinity between the blocks driving them part is balanced by a restorative force deriving from the chemical bond between the blocks. These systems are attracting much interest because of their possible role in nanoelectronic fabrication. This form of self-assembly can obtain highly regular nanopatterns in certain circumstances where the orientation and alignment of chemically distinct blocks can be guided through molecular interactions between the polymer and the surrounding interfaces. However, for this to be possible, great care must be taken to properly engineer the interactions between the surfaces and the polymer blocks. The optimum methods of structure directing are chemical pre-patterning (defining regions on the substrate of different chemistry) and graphoepitaxy (topographical alignment) but both centre on generating alignment through favourable chemical interactions. As in all self-assembling systems, the problems of defect formation must be considered and the origin of defects in these systems is explored. It is argued that in these nanostructures equilibrium defects are relatively few and largely originate from kinetic effects arising during film growth. Many defects also arise from the confinement of the systems when they are ‘directed’ by topography. The potential applications of these materials in electronics are discussed.     

Electrostatic Adsorption of a Colloidal Sintering Agent on Silicon Nitride Particles

Pressureless sintering of silicon nitride requires addition of sintering agents. The main part of this study was done in order to homogenize the distribution of sintering agents, in this case Y₂O₃, in a silicon nitride matrix. Colloidal 10-nm Y₂O₃ Particles were electrostatically adsorbed on Si₃N₄ particle surfaces. The adsorption was studied by X-ray fluorescence analysis and electrophoretic measurements. Addition of Y₂O₃ sol to a Si₃N₄ suspension decreased the viscosity of the suspension. The slip casting properties of Si₃N₄ suspensions with added Y₂O₃ sol were examined, and the homogeneity of Y₂O₃ in the green compacts was compared with conventionally prepared samples. An improved microstructural homogeneity was obtained when Y₂O₃ sol particles were adsorbed on the Si₃N₄ particle surfaces.     

Interpretation of DTA Experiments Used for Crystal Nucleation Rate Determinations

An analysis is presented of two schemes which have been proposed for the determination of the temperature dependence of homogeneous crystal nucleation rates in glasses via DTA measurements. The first method is based upon the postulate that the inverse of the temperature at which the DTA crystallization rate is maximum, T ¹_p, will increase monotonically as the number density of nucleated particles increases. The second method is based on the observation that the intensity at T _p (peak height) increases as T _p grows. The validity of both of these methods is assessed for inorganic glasses for two specific crystal growth models.     

Surface properties of commercial polymer films following various gas plasma treatments

Surface properties of a number of commercial thermoplastic polymer films were investigated before and after brief exposures to RF induced, low temperature gas plasmas. Water wettability and adhesion of vapor deposited aluminum to thin films (8–12 micron) of polyethylene, polypropylene, polyester, polysulfone, polycarbonate, and polyvinylidene fluoride films were studied before and after treatments with oxygen, 96% CF₄/4% O₂, and helium plasmas. Treatment with oxygen plasmas showed the greatest change in water wettability for polyvinylidene fluoride and polypropylene films, while treatment with 96% CF₄/4% O₂ showed dramatic changes in wettability of polycarbonate, polysulfone, and polystyrene. Excellent adhesion of aluminium was found for polymers that had been previously exposed to gas plasmas.     

The electroactive species in the catalysis of cyclohexadiene to benzene by Rh2(TM4) 4 +2 (TM4=2,5-diisocyano-2,5-dimethylhexane)

Upon further investigation of the recently reported electrocatalytic oxidation of 1,4-cyclohexadiene to benzene by Rh₂(TM4) ₄ ⁺² (TM4=2,5-diisocyano-2,5-dimethylhexane), we have obtained data which strongly implicates the 2e^– oxidized d⁷-d⁷ complex as the electroactive species. This contrasts with the original report which suggested that the le^– oxidized d⁷-d⁸ radical acted as the key species via hydrogen atom abstraction from 1,4-cyclohexadiene. A possible mechanism for the catalysis is proposed.