Металлографические исследования модифицирующей способности прутков из алюминиевых сплавов, полученных методом совмещенного литья и прокатки-прессования

Proposed new ways of obtaining rods-modifiers from aluminum and aluminum alloys. Were researched of their modifying ability and tested in industrial conditions modification technology in the production of aluminum alloy ingotsПредложены новые способы получения прутков-модификаторов из алюминия и алюминиевых сплавов. Была изучена их модифицирующая способность и опробована в промышленных условиях технология модифицирования при производстве слитков из алюминиевых сплаво

Investigation into the Influence of the Degree of Grinding of the Ingot Grain Structure of the 6063 Alloy on Its Plasticity, Extruding Parameters, and Properties of Extruded Profiles

As a result of an analysis of scientific and technical literature and practical data, it is found that changing the casting parameters for ingots using different designs of crystallizers makes it possible to vary the degree of refinement of the grain structure of ingots in a sufficiently wide range, which should be reflected in the conditions of extrusion of aluminum alloy profiles and their physicomechanical characteristics. Therefore, the purpose of this research is to assess the influence of the degree of grinding for the ingot grain structure of alloy 6063 on the deformation and speed parameters of extrusion and the mechanical properties of profiles. Several parties of 178-mm diameter ingots of 6063 alloy cast under industrial conditions, as well as profiles formed by direct extrusion using a horizontal hydraulic press with a force of 18 MN subjected to quenching and aging, are used. The grain size in homogenized ingots is evaluated by optical microscopy using an Olimpus optical microscope, and tests of mechanical properties are performed using an Inspect 20 kN-1 universal testing machine. It is established that the initial grain size in the ingot structure strongly affects both the ingot plasticity during extrusion and final structure and mechanical properties of profiled products made of aluminum alloys. When analyzing these results, it is possible to conclude that an increase in strength characteristics of extruded products made of ingots with a more refined structure is due to the fact that a fine grain is retained in the metal structure after its deformation, while the cast metal plasticity rises with an increase in the degree of grinding the grain structure in the ingot. In connection with this fact, an increase in the efficiency of quenching the profiled products and metal outflow rate during the extrusion take place

Development and Research of Technology Manufacturing of Semi-Finished Products from Solder Alloys Based on Silver

Proposed new compositions of solder alloys based on silver. Developed technological schemes of production of wire diameter 1,2 mm. Developed scheme of production of wire diameter 1,2 mm from alloy SAg-40I with operation combined casting, rolling and extruding. Modeling of temperature-rate parameters of the process of combined casting, rolling and extruding has been made. Designed and constructed the installation CCRE-80. The analysis of the structure and properties of semi-finished solder alloys based on silver has been done.Предложены новые составы припойных сплавов на основе серебра. Разработаны технологические схемы производства проволоки диаметром 1,2 мм. Разработана схема производства проволоки диаметром 1,2 мм из сплава ПСр-40И с применением операции совмещенного литья, прокатки и прессования. Проведено моделирование температурно- скоростных параметров процесса совмещенного литья, прокатки и прессования. Спроектирована и изготовлена установка СЛИПП-80. Проведен анализ структуры и свойств полуфабрикатов из припойных сплавов на основе серебра

Применение моделирования при проектировании инструмента для прессования полых профилей из алюминиевых сплавов

In order to simulate the pressing of hollow profiles made from aluminum alloys, the previously developed design algorithms for the pressing tool and the QForm software were utilized. The objective of this study was to enhance the quality and decrease the design timeintervals for pressing tools used in the industrial production of aluminum alloy profiles. A novel design procedure for a combined tool, along with the technology of semi-continuous pressing with welded hollow profiles made from aluminum alloys, was proposed. This was achieved using the QForm software, which enables efficient calculations and adjustments of pressing parameters and tool geometry through a dialog interface. The developed algorithm and design procedures enable the drawing of hollow profiles, technological calculations of pressing parameters, selection of a suitable horizontal hydraulic press, matrix and splitter design, determination of strength parameters, assessment of equipment load, and preparation of working drawings for the pressing tool. In order to validate the effectiveness of the design procedure, it was applied to typical hollow profiles fabricated on a commercial scale. Two variations of the pressing tool design were examined. Simulation results obtained from QForm Extrusion software, specifically designed for pressing analysis, revealed that the initial design of the tool, with predetermined technological parameters and geometry of the splitter and matrix channels, resulted in uneven flow of profile elements and temperature distribution. However, by adjusting the tool parameters, it was possible to achieve a straight profile exit from the matrix and a uniform temperature distribution across its cross section. Industrial verification of the designed tool, utilizing a 33 MN hydraulic horizontal press for pressing profiles made from alloy 6063, demonstrated that significant modifications to the matrix and splitter were not necessary. By employing the proposed pressing tool design, batches of products were successfully manufactured in compliance with the required technical specifications, while reducing the design time intervals of the pressing tool by approximately 50 %.Для моделирования процесса прессования полых профилей из алюминиевых сплавов использованы разработанные ранее алгоритмы проектирования прессового инструмента и программный комплекс «QForm». Целью проведенных исследований являлось повышение качества и снижение сроков проектирования прессового инструмента для промышленных условий производства профилей из алюминиевых сплавов. Предложены новая методика проектирования комбинированного инструмента и технологии для полунепрерывного прессования со сваркой полых профилей из алюминиевых сплавов с помощью программного комплекса «QForm», который позволяет в диалоговом режиме оперативно проводить многовариантные расчеты с последующей, если необходимо, корректировкой технологических параметров прессования и геометрии инструмента. Созданы алгоритм и процедуры проектирования, которые дают возможность выполнить чертеж полого профиля, осуществить технологические расчеты параметров прессования и выбор горизонтального гидравлического пресса, спроектировать матрицу и рассекатель, провести прочностные расчеты, определить силовую загрузку оборудования и подготовить рабочие чертежи прессового инструмента. Для проверки работоспособности разработанной методики проектирования приведен пример ее реализации для одного из типовых полых профилей, изготавливаемого в промышленном производстве. Рассмотрено проектирование двух вариантов прессового инструмента. С помощью моделирования с использованием программы «QForm Extrusion», предназначенной для анализа процессов прессования, установлено, что первый вариант конструкции инструмента при заданных технологических параметрах и геометрии каналов рассекателя и матрицы приводит к неравномерности истечения различных элементов профиля и температур. В результате проведенной корректировки параметров инструмента удалось добиться прямолинейности выхода профиля из матрицы и равномерности распределения температур по его сечению. Промышленное опробование спроектированного инструмента на гидравлическом горизонтальном прессе с усилием 33 МН для прессования профиля из сплава 6063 показало, что существенной доработки матрицы и рассекателя не требуется. С применением предложенной конструкции прессового инструмента получены партии продукции, соответствующей требованиям действующих технических условий, при этом сроки проектирования прессового инструмента сокращены практически в 2 раза

ПРОГНОЗИРОВАНИЕ СВОЙСТВ МЕТАЛЛА ПРИ СОВМЕЩЕННОЙ ОБРАБОТКЕ СПЛАВОВ СИСТЕМЫ Al–РЗМ НА ОСНОВЕ ПОЭТАПНОЙ ОЦЕНКИ ИХ МЕХАНИЧЕСКИХ ХАРАКТЕРИСТИК

The data of experimental studies on determining the mechanical properties of long-length deformed semifinished products in a form of bars and wire made of alloys of aluminum with rare-earth metals, which are fabricated using the combined treatment methods, are presented. The application of the combined technology of casting, rolling, and pressing makes it possible to increase the strength of hot-extruded rod by 15–20 % on average compared with combined rolling–extruding the cast billet formed in an electromagnetic crystallizer. It is also shown that a decrease in the REM content in the alloy leads to the strength reduction and an increase in plastic characteristics. Herewith, it is possible to control the level of physicomechanical characteristics of the final product varying the summary deformation ratio during drawing and applying annealing.Приведены данные экспериментальных исследований по определению механических свойств длинномерных деформируемых полуфабрикатов в виде прутков и проволоки из сплавов алюминия с редкоземельными металлами, полученных с использованием методов совмещенной обработки. Применение совмещенной технологии литья, прокатки и прессования дает возможность увеличить прочность горячепрессованных прутков в среднем на 15–20 % по сравнению с совмещенными процессами прокатки и прессования литой заготовки, полученной в электромагнитном кристаллизаторе. Показано также, что уменьшение содержания РЗМ в сплаве приводит к снижению прочностных и повышению пластических характеристик. При этом, варьируя величиной суммарной степени деформации при волочении и применяя отжиги, можноуправлять уровнем физико-механических характеристик конечной продукции

РАСЧЕТНО-ЭКСПЕРИМЕНТАЛЬНАЯ ОЦЕНКА УСЛОВИЯ РЕАЛИЗАЦИИ ПРОЦЕССА СОВМЕЩЕННОЙ ПРОКАТКИ-ПРЕССОВАНИЯ С ИСПОЛЬЗОВАНИЕМ МЕТОДА БАЛАНСА МОЩНОСТЕЙ

The paper presents the results obtained when solving the problem consisting in determination of the combined extrolling process implementation. The components of a total capacity for the process studied were written in analytical form, their calculation and analysis of the effect of specific factors on implementation of the combined extrolling process was made on PC using a specially developed program. A quantitative evaluation of the process feasibility was made using safety factor as a major criterion for the conditions of aluminum alloy combined extrolling at the pilot combined processing plant.Приведены результаты решения задачи по определению возможности реализации процесса совмещенной прокатки-прессования (СПП). В аналитическом виде записаны составляющие полной мощности для исследуемого процесса, с помощью разработанной программы на ЭВМ произведен их расчет и проанализировано влияние отдельных факторов на осуществление процесса СПП. Для условий совмещенной прокатки-прессования алюминиевых сплавов на опытно-промышленной установке совмещенной обработки дана количественная оценка возможности реализации процесса с использованием в качестве основного критерия коэффициента запаса мощности

Gender-specific hip fracture risk in community-dwelling and institutionalized seniors age 65years and older

Summary: In this study of acute hip fracture patients, we show that hip fracture rates differ by gender between community-dwelling seniors and seniors residing in nursing homes. While women have a significantly higher rate of hip fracture among the community-dwelling seniors, men have a significantly higher rate among nursing home residents. Introduction: Differences in gender-specific hip fracture risk between community-dwelling and institutionalized seniors have not been well established, and seasonality of hip fracture risk has been controversial. Methods: We analyzed detailed data from 1,084 hip fracture patients age 65years and older admitted to one large hospital center in Zurich, Switzerland. In a sensitivity analysis, we extend to de-personalized data from 1,265 hip fracture patients from the other two large hospital centers in Zurich within the same time frame (total n = 2,349). The denominators were person-times accumulated by the Zurich population in the corresponding age/gender/type of dwelling stratum in each calendar season for the period of the study. Results: In the primary analysis of 1,084 hip fracture patients (mean age 85.1years; 78% women): Among community-dwelling seniors, the risk of hip fracture was twofold higher among women compared with men (RR = 2.16; 95% CI, 1.74-2.69) independent of age, season, number of comorbidities, and cognitive function; among institutionalized seniors, the risk of hip fracture was 26% lower among women compared with men (RR = 0.77; 95% CI: 0.63-0.95) adjusting for the same confounders. In the sensitivity analysis of 2,349 hip fracture patients (mean age 85.0years, 76% women), this pattern remained largely unchanged. There is no seasonal swing in hip fracture incidence. Conclusion: We confirm for seniors living in the community that women have a higher risk of hip fracture than men. However, among institutionalized seniors, men are at higher risk for hip fracture

Vitamin D supplementation and breast cancer prevention : a systematic review and meta-analysis of randomized clinical trials

In recent years, the scientific evidence linking vitamin D status or supplementation to breast cancer has grown notably. To investigate the role of vitamin D supplementation on breast cancer incidence, we conducted a systematic review and meta-analysis of randomized controlled trials comparing vitamin D with placebo or no treatment. We used OVID to search MEDLINE (R), EMBASE and CENTRAL until April 2012. We screened the reference lists of included studies and used the “Related Article” feature in PubMed to identify additional articles. No language restrictions were applied. Two reviewers independently extracted data on methodological quality, participants, intervention, comparison and outcomes. Risk Ratios and 95% Confident Intervals for breast cancer were pooled using a random-effects model. Heterogeneity was assessed using the I2 test. In sensitivity analysis, we assessed the impact of vitamin D dosage and mode of administration on treatment effects. Only two randomized controlled trials fulfilled the pre-set inclusion criteria. The pooled analysis included 5372 postmenopausal women. Overall, Risk Ratios and 95% Confident Intervals were 1.11 and 0.74–1.68. We found no evidence of heterogeneity. Neither vitamin D dosage nor mode of administration significantly affected breast cancer risk. However, treatment efficacy was somewhat greater when vitamin D was administered at the highest dosage and in combination with calcium (Risk Ratio 0.58, 95% Confident Interval 0.23–1.47 and Risk Ratio 0.93, 95% Confident Interval 0.54–1.60, respectively). In conclusions, vitamin D use seems not to be associated with a reduced risk of breast cancer development in postmenopausal women. However, the available evidence is still limited and inadequate to draw firm conclusions. Study protocol code: FARM8L2B5L

Before and after hip fracture, vitamin D deficiency may not be treated sufficiently

Summary: Our findings show that only about 20% of seniors receive vitamin D supplementation prior to their index hip fracture or after the event. We further confirm the high prevalence of severe vitamin D deficiency in this population and show that those who receive supplementation have significantly higher 25-hydroxyvitamin D (25(OH)D) status. Introduction: The aim of this study is to assess current practice in pre- and post-hip fracture care practice with respect to vitamin D supplementation. Methods: We surveyed 1,090 acute hip fracture patients age 65 and older admitted to acute care for hip fracture repair; 844 had serum 25-hydroxyvitamin D levels measured upon admission to acute care, and 362 agreed to be followed at 12month after their hip fracture. Prevalence of vitamin D supplementation was assessed upon admission to acute care (at the time of hip fracture), upon discharge from acute care, and at 6 and 12months follow-up. Results: Of 1,090 acute hip fracture patients (mean age 85years, 78% women, 59% community-dwelling), 19% had received any dose of vitamin D prior to the index hip fracture, 27% (of 854 assessed) at discharge from acute care, 22% (of 321 assessed) at 6month, and 21% (of 285 assessed) at 12month after their hip fracture. At the time of fracture, 45% had 25(OH)D levels below 10ng/ml, 81% had levels below 20ng/ml, and 96% had levels below 30ng/ml. Notably, 25(OH)D levels did not differ by season or gender but were significantly higher among 164 hip fracture patients, with any vitamin D supplementation compared with 680 without supplementation (19.9 versus 10.8ng/ml; p < 0.0001). Conclusion: Only about 20% of seniors receive vitamin D at the time of their fracture and after the event. This is despite the documented 81% prevalence of vitamin D deficiency. Interdisciplinary efforts may be warranted to improve vitamin D supplementation in seniors both before a hip fracture occurs and afte