Clean-sheared and rectangular edges through counter-shaving

A various number of products exist which require a clean-sheared edge due to function or surface feel. Traditionally, these parts are produced on fine blanking presses with three separate and distinct movements. Shaving, in particular counter-shaving is a shearing operation to improve the edge quality of a blanked part or punched hole. This paper introduces a progressive die tool to realize the counter-shaving process on a single acting press. Advancing the chip flow through choosing a cutter angle can achieve up to a 85% clean-sheared edge and rectangular edge. Thereby, a sharp-edged transition—without any rollover depth—between the upper surface of the sheet metal and the sheared-edge are formed. The end of the clean-sheared edge is followed by a tear which shapes a burr in the form of a triangular lappet, which can be deburred in a subsequent vibratory grinding process. Experimental results of different process parameters for two sheet metal materials at three thicknesses are discussed and compared to finite element calculations. The presented research work was supported by the German Research Foundation (DFG).     

Determination of True Stress-Strain-Curves and Normal Anisotropy in Tensile Tests with Optical Strain Measurement

This paper describes a method to measure the flow curve which undergoes necking and normal anisotropy as a function of equivalent strain using an optical measurement system. The flow stress was determined by modifying Siebel and Schwaigerer's model. Normal anisotropy was regarded as a function of equivalent strain. Comparing with the experiment of the stretch forming process, the simulation using improved material properties shows the better strain distribution than the results using conventional material properties in high strain areas.     

The purification of copper refinery electrolyte

The phrase “purification of copper refinery electrolyte” is misleading since typically, impurities are controlled by withdrawing a bleedstream of the circulating electrolyte. However, solvent extraction and ion exchange have also found some application in impurity control. This article describes conventional practice, including treatment of the bleedstream, and other attempts at electrolyte purification. Impurities to be discussed include Sb, Bi, As, Ni, Ca, ammonia, and organic fragments generated from hydrolysis of conventional cathode growth-modifying addition agents. For more information, contact J.E. Hoffmann, James E. Hoffmann & Associates Co., P.O. Box 420545, Houston, TX 77242-0545; (281) 493-9441; fax (713) 780-0761; e-mail jehentp@aol.com.     

Understanding automatic generation control

The authors describe what automatic generation control (AGC) might be expected to do, and what may not be possible or expedient for it to do. The purposes and objectives of AGC are limited by physical elements involved in the process and, hence, the relevant characteristics of these elements are described. For reasons given, it is desired that AGC act slowly and deliberately over tens of seconds or a few minutes. From a perspective of utility operations, there is no particular economic or control purpose served by speeding up the AGC action     

Illness-specific control issues in patients with vertigo as the main symptom

The study explored the relationship between health locus of control and anxiety in 90 patients with the chief complaint of dizziness/vertigo. The patients were subjected to a neurological examination, including standardised history, physical examination, electronystagmography with caloric testing and posturography, auditory and visually brainstem-evoked responses, masseter reflex, vertebrobasiliar transcranial Doppler, optional: cranial imaging (CCT/MRI), cardial diagnostic, and a psychiatric-psychodynamic examination (including psychometric tests: STAI-G X2, KKG, SBA-S). The whole group of patients (psychogenic and organic dizziness) had a specific pattern of health locus of control: "double health external" (Type IV-Wallston and Wallston 1982). Patients with psychogenic dizziness showed a higher score of external locus of control (chance) compared with the patients with organic dizziness. High anxiety scores were accompanied by high scores of external locus of control (powerful others and chance) above all in the patients with psychogenic dizziness. Implications for therapy are discussed.     

Testing children for genetic predispositions: is it in their best interest?

Serotonin (5-hydroxytryptamine; 5-HT), an endogenous and ubiquitous monoamine, has become a subject of "explosive" research. Though its vasoconstrictor properties were first noticed in defibrinated or clotted blood, 5-HT was discovered 75 years later going through several denominations such as "enteramine, serotonin or 5-HT". Once confirmed that serotonin, enteramine and 5-HT were the same substance, the compound was synthesized and efforts with a view to analyze 5-HT receptors were performed. On the basis of the actions of 5-HT and other drugs on several smooth muscle experimental preparations, it was originally suggested that 5-HT could act via different receptors. Thus, Gaddum and Picarelli proposed the "D" and "M" classification based on the differential sensitivity of guinea pig ileum 5-HT-induced contraction to some drugs. Later on, this classification was confronted with the new Peroutka's 5-HT, and 5-HT2 classification derived from radioligand binding studies. Since these 5-HT receptors were being referred to by many names, an international committee formulated some criteria for the characterization and a framework for the nomenclature of 5-HT receptors into 5-HT1, 5-HT2 and 5-HT3 categories. More recently, functional evidence unrelated to activation of the above 5-HT receptor types was given and a new 5-HT (5-HT4) receptor was proposed to exist. From this stage, molecular biologists have been cloning several 5-HT receptors which are different from the various receptors (sub)types characterized thus far. This review is focused on the discovery of 5-HT and the evolution of the classification of 5-HT receptors, from historical remarks to the modern concepts about receptor characterization; furthermore, the relevance of this development to medical research is considered.     

Control of the aluminium-oxygen reaction in pure iron melts

Modified electrochemical oxygen sensors based on CaO-doped ZrO₂ and Y₂O₃-doped ThO₂ were developed and applied to study the aluminium-oxygen reaction in pure liquid iron with special regard to the provision of reliable experimental conditions and the attainment of true chemical equilibrium. The sensors represent valuable tools particularly for EMF long-term measurements over several hours. At 1600 °C, values of the constant and of the interaction parameters and were determined. When Fe-O-Al melts are covered with a slag phase at an activity a(Al₂O₃) < 1, e.g., CaO-saturated CaO-Al₂O₃ slag, the Al-O relationship in the iron may nevertheless be controlled by an equilibrium oxide phase at an activity a(Al₂O₃) = 1, presumably represented by inclusion particles consisting of pure Al₂O₃.     

Control of the chromium-oxygen reaction in pure iron melts

Oxygen activities in Fe-O-Cr melts, equilibrated with chromium oxide, were determined as a function of chromium content by EMF measurements using ZrO₂(CaO) plug-type sensors with a Cr-Cr₂O₃ reference. Plug-type sensors with or without Cr₂O₃ saturator were used in the experiments. From the experimental results values for the activity coefficient f_O and the interaction parameters and were evaluated. Raoultian chromium activity features a slight positive deviation from ideal solution behaviour in the temperature range from 1550 to 1650°C. Taking into account the calculated interaction parameters, the equilibrium constant K_Cr-O was redetermined at 1550 to 1650°C. In comparison with previous studies a better agreement was obtained with existing thermochemical data.