Flexibility in metal forming Yang, D.Y.; Bambach, M.; Cao, J. ...
CIRP annals,
2018, 2018-00-00, Letnik:
67, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Flexibility in metal forming is needed more than ever before due to rapidly changing customer demands. It paves the way for a better control of uncertainties in development and application of metal ...forming processes. Although flexibility has been pursued from various viewpoints in terms of machines, material, process, working environment and properties, etc., a thorough study of the concept was undertaken in order to with problems of manufacturing competiveness and tackle new challenges of manufacturing surroundings. Therefore, in this paper, flexibility in forming is reviewed from the viewpoints of process, material, manufacturing environment, new process combinations and machine–system–software interactions.
Velocity is probably the most important parameter in manufacturing, influencing performance, cost, productivity, energy and resources efficiency as well as safety and environmental issues. This paper ...presents basic phenomena as well as other important effects which are linked to velocity as a process parameter. In addition, applications, for example superplastic forming or high speed cutting, which have been founded on uncommon process velocities are discussed in the context of technological developments which have taken place over the past several years.
Sheet metal forming at elevated temperatures Neugebauer, R.; Altan, T.; Geiger, M. ...
CIRP annals,
2006, 2006-00-00, Letnik:
55, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
Due to the need to significantly reduce the part weights in automotive manufacturing, the use of lightweight materials becomes ever more important. Unfortunately, these materials are often associated ...with a limited cold formability. Due to this fact, production of large, complex sheet metal components using forming technology frequently entails increased expenditures. Moreover, processing high-strength materials requires correspondingly high processing forces and pressures. In order to find a solution to counter the disadvantages mentioned above, the use of elevated temperatures as a process parameter in forming operations represents a potential solution approach. The following paper will give an overview about research activities in the field of forming operations at elevated temperatures.
South Africa has significant titanium reserves and is developing strategies to not only provide this raw material on global markets, but to manufacture complex titanium alloy products and participate ...fully in global supply chains. Pursuing more sustainable process chains, manufacturers are constantly striving to enhance the resource efficiency of their high added value processes. Titanium alloys are used comprehensively in aerospace and biomedical applications, due to its favourable strength-to-weight ratio, corrosion resistance and biocompatibility. These properties, however, contribute to the manufacturing challenges, classifying it as a difficult-to-machine material. Various input factors affect the efficiency of a hybrid process chain. The objectives of this multidisciplinary research group were to demonstrate the reduction of material wastage by up to 50% and machining time up to 20% for selected titanium components. The results clearly demonstrate the ability to increase the technology readiness levels of the selected components and to develop competitive hybrid titanium process chains that will enable South Africa to integrate more into global manufacturing value chains.
Metal forming processes operate in conditions of uncertainty due to parameter variation and imperfect understanding. This uncertainty leads to a degradation of product properties from customer ...specifications, which can be reduced by the use of closed-loop control. A framework of analysis is presented for understanding closed-loop control in metal forming, allowing an assessment of current and future developments in actuators, sensors and models. This leads to a survey of current and emerging applications across a broad spectrum of metal forming processes, and a discussion of likely developments.
Physiological changes in old age: loss of muscle mass; reduction in bone mass; percentage of fat increased; lower amount of body water; lack of thirst; diminishing kidney function (caution: ...sufficient intake of fluids: 1.5-2 l and moderate intake of protein 8 g/kg body weight); reduced secretion of digestive enzymes, delayed emptying of stomach (which means premature feeling of repletion). Lack of fluids and nutrition is therefore likely. Daily intake of 1,500 kcal and 1.5-2 l fluids is necessary. An indicator for malnutrition is low body weight (defined for persons older than 65 years of age as BMI < 20) and a protein serum concentration < 35 g/l. Malnutrition carries an increased risk of infections, falling and fractures, bed sores, anemia, decompensation of chronic diseases. 10-20% of subjects over 80 years of age show signs of malnutrition, 40-60% of subjects in care institutions or hospitals. There are regressive changes in the locomotor and the nervous system of the elderly which have an effect on physical fitness. These changes reduce strength, endurance, proprioceptive capacity (e.g. coordination, balance) and mobility. Exercise in the old and very old should increase skeletal muscle strength in particular and improve coordination and balance. Regular physical exercise and moderate training has a positive effect on mobility and thereby improves independence and reduces falls. Moreover, it has a positive effect on cardiac output, maximum heart rate, stroke volume and the risk of a cardiovascular event and mortality can be reduced. Moreover, moderate physical exercise is often more effective in treating chronic disease than drug therapy e.g. heart failure, coronary heart disease, asthma/COPD, stroke, diabetes mellitus Type 2, degenerative diseases of the joints, depression and others. Examine cardiovascular risks in persons over the age of 50 before beginning physical exercise. Avoid maximum stress levels.
The part "Special pharmacology of the aged" of this guideline contains recommendations for typical conditions in the family doctors practice: in the January issue 2009 dementia and Morbus Parkinson, ...in this issue osteoporosis and urinary incontinence and in the next issue rectal incontinence and obstipation. This issue of the IJCPT contains the third part of the Pharmacotherapy guidelines for the aged by family doctors for family doctors. Part 3: Osteoporosis and urinary incontinence. Osteoporosis is a systematic disease characterized by low bone mass and declining bone structure. Exercise, adequate diet, nicotine abstinence as well as reduction of alcohol consumption may counteract the progression of the disease. Osteoporosis manifests in bone fractures with minimal trauma. Attention must be given to the risk of falling, e.g., by avoiding drugs that increase the risk of falling: e.g., psychotropic agents, analgesic drugs and antiarrhythmic agents. Specific osteoporosis medication e.g. calcium, vitamin D, biphosphonates and SERM (selective estrogen receptor modulators) is evaluated by family doctors according to indication, dosage, contraindications, long-term therapy and nature of any fracture. Duration of therapy is at least 3 - max. 5 years followed by reassessment of indication. There are 3 types of urine incontinence (urge-, stress-, and overflow-incontinence). Another standardization of urinary incontinence follows dysfunctions of the pelvic floor: detrusor muscle-dependent, due to sphincter spasm, prostate gland dependent. Urge incontinence with a dysfunction of the detrusor muscle is the most common type. Mixed types are frequent. Non-drug measures (e.g. pelvic muscle training, bladder training, toilet training are first choice treatments. Drug therapy (estrogen, imipramine) are without proven effect.
Part C of the guideline is preceded by Part B General Pharmacology IJCPT. 2008; 46: 600 - 617. Included in Part C are practical guidelines for improving the therapy of some age-specific diseases and ...problems commonly encountered in general practice. The article in this issue is dedicated to the therapy of Dementia and M. Parkinson. Further guidelines for the other age specific diseases and problems named above will be published in the following issues of IJCPT. An important feature of these guidelines are the inclusion of Levels of Evidence and of the Strength of Recommendations for the therapy which are shown when reliable studies are available. (For both see levels of evidence at the end of this article.).
This article contains the 4th part of the Pharmacotherapy Guidelines for the Aged by Family Doctors for Family Doctors. Part 4 is dedicated to fecal incontinence and chronic constipation. The ...diagnostic categories are divided according to severity and dysfuntion of bowel and pelvic floor, sphincter and neural control. Therapy is also outlined. Importance is given to patient history, in particular the use and abuse of drugs that stimulate peristalsis and promote constipation. Therapy in the elderly is guided by the maxim: use the most conservative therapy possible, where stool training has considerable importance. Drug therapy based on symptoms can only be recommended when non-drug measures continue to fail. In patients with fecal incontinence: 1) opiates (which reduce colonic motility), 2) loperamide (which has the capacity to dilate the rectum) and 3) anion exchangers which have the capacity to prevent cholonic diarrhea. In patients with chronic obstipation: 1) trial: stool-forming laxatives (ensure intake of sufficient amount of fluids) 2) trial: laxatives with an osmotic effect and 3) trial: stimulating laxatives (beware abuse, do not use in cases of acute abdomen).
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