ОСОБЕННОСТИ ТЕХНОЛОГИИ ПОЛУЧЕНИЯ ПЛАСТИЧЕСКИМ ДЕФОРМИРОВАНИЕМ ЗУБЬЕВ СЕГМЕНТОВ РЕЖУЩИХ АППАРАТОВ ЗЕРНО- И КОРМОУБОРОЧНОЙ ТЕХНИКИ

The paper presents a new technology for formation of segment teeth of agricultural machinery by plastic deformation instead of mechanical machining. Changes in segment design that permit to improve its operation and cutting quality are given in the paper. The paper describes advantages of the new technology allowing to ensure significant economical effect and increase sickle endurance and longevity. Power parameters of deformation process are theoretically calculated and justified by the experiments. The paper contains results of comparative sickle testings which have been manufactured in accordance with conventional new technologies.Предложена новая технология формообразования пластическим деформированием зубьев сегментов режущих аппаратов сельскохозяйственной техники вместо механической обработки. Приведены изменения конструкции сегмента, позволяющие улучшить условия его работы и качество резания. Описаны преимущества новой технологии, позволяющие достичь значительного экономического эффекта и увеличения износостойкости и долговечности режущих аппаратов. Рассчитаны теоретически и обоснованы экспериментами энергосиловые параметры процесса деформирования. Представлены результаты сравнительных испытаний сегментов, изготовленных по традиционной и новой технологиям

Особенности изгиба полосы в валках

The paper describes edge bending of narrow high strip with the help of bending-rolling method in the rolls which are rotating with different peripheral velocities. An equation is proposed with the purpose to determine dependence of reduction, which is necessary in order to ensure strip bending, on the value of contact friction. Theoretical calculation and experimental analysis of the obtained data have been carried out.Results of the investigations permit to make a conclusion that while changing reduction value and coefficient of contact friction it is possible to obtain bending of a strip along its whole length with the required radius.Описан способ изгиба узкой высокой полосы на ребро методом гибки-прокатки в валках, вращающихся с разными окружными скоростями. Предложено уравнение для определения зависимости обжатия, необходимого для обеспечения изгиба полосы, от величины контактного трения. Проведен теоретический расчет и выполнена экспериментальная проверка полученных данных.Результаты проведенной работы позволяют сделать вывод о том, что, изменяя величину обжатия и коэффициента контактного трения, можно добиться изгиба полосы по всей длине на необходимый радиус

CRYOBALLOON ABLATION IN RUSSIAN SITES OF INTERVENTIONAL ATRIAL FIBRILLATION MANAGEMENT TREATMENT: RESULTS OF THE FIRST NATIONWIDE SURVEY

Aim. The results of cryoballoon ablation (CBA) are known from the studies performed in the experienced centers of catheter treatment of atrial fibrillation (AF). The current study presents the results of CBA in real practice in centers with various experienceMaterial and methods. Among 62 Russian sites performing catheter treatment of AF, in 15 the CBA methods were in use to isolate pulmonary veins, in the years 2012-2014. Centers staff were surveyed for the detailed description of all performed CBA till 10.2014. The questionnaire included 74 lines about the centers experience, patients properties and ablation procedures, management of patients and complications. At the second step the questionnaire was used about complications.Results. Thirteen centers provided full data on all patients with CBA (457 procedures; 94% for paroxysmal AF; >95% CBAs in Russia). Six centers were marked as highly experienced for CBA for AF (mean 414,2±339,4 ablations for AF per year), and 7 — with lesser experience (33,2±34,3 ablations for AF per year). Ten centers provided the results of 6/12 month observation, and 11 centers — detalization of the complications data. there were no statistically significant differences in arrhythmia absence in patients from both types of centers (61,9±10,0 versus 61,3±30,4%). Serious complications developed in 1,5% of patients (4 tamponades, 2 strokes and 1 diaphragmal nerve palsy) and were similarly spread among more and less experienced centers (1,4% vs. 2%, p>0,05). Minor adverse events (vascular, transient diaphragm nerve palsy, transient hemoptysis) were found in 37 (8%) patients and were more common in more experienced (teaching) centers. Overall frequency of adverse events and of vascular events was higher in females than males (12% and 4,9% vs. 6% and 0%, resp.; p<0,05).Conclusion. In the real clinical practice CBA is performed with acceptable efficacy and moderate frequency of adverse events development. In less experienced centers of catheter treatment of AF the prevalence of serious adverse events does not differ from less experienced. Women develop vascular complications more often

Ventricular arrhythmias. Ventricular tachycardias and sudden cardiac death. 2020 Clinical guidelines

Russian Society of Cardiology (RSC).With the participation of Russian Scientific Society of Clinical Electrophysiology, Arrhythmology and Cardiac Pacing, Russian Association of Pediatric Cardiologists, Society for Holter Monitoring and Noninvasive Electrocardiology.Approved by the Scientific and Practical Council of the Russian Ministry of Health

TECHNOLOGICAL PECULIARITIES IN RESPECT OF OBTAINING SEGMENT TEETH OF GRAIN AND FODDER HARVESTING MACHINERY SICKLES BY PLASTIC DEFORMATION

The paper presents a new technology for formation of segment teeth of agricultural machinery by plastic deformation instead of mechanical machining. Changes in segment design that permit to improve its operation and cutting quality are given in the paper. The paper describes advantages of the new technology allowing to ensure significant economical effect and increase sickle endurance and longevity. Power parameters of deformation process are theoretically calculated and justified by the experiments. The paper contains results of comparative sickle testings which have been manufactured in accordance with conventional new technologies

ACHIEVEMENT OF DIMENSIONAL ACCURACY OF LENGTH VARIABLE THICKNESS STRIP AT ROLLING

It is established that the process of symmetrical rolling is accompanied by high metal pressure on the rolls, which leads to wear on their working surface. To reduce the metal pressure, the tension of the strip ends is applied. With a minimum forward tension, the deformation conditions are realized in the case of a discrepancy between the circumferential speeds of the working rolls. It is determined that the precision of products depends on the amount of advance and this must be taken into account when rolling with variable reduction. An equation for determining the instantaneous advance of the metal in the cross section of the exit from the deformation center during the rolling of profiles of variable cross section with increasing compression is presented. It has been theoretically proved that in order to reduce tool wear and to achieve the specified dimensional accuracy of the rolling profile, it is quite sufficient to roll the strip in the last pass with a minimum unit reduction of not more than 0,5 mm

FEATURES OF ROLLING OF STRIPS OF VARIABLE THICKNESS WITH A LOCAL BEND

Schemes of rolling of striped blanks on swage at various values of their front tension are considered