Numerical analysis of the cross wedge rolling process (CWR) for a stepped shaft

The paper presents the results of numerical modeling of a complex CWR process for producing a stepped shaft. The modeling was performed using the Finite Element Method (FEM) based commercial software Simufact.Forming. The numerical analysis enabled the determination of changes in shape of the workpiece, strain and temperature distributions, as well as variations in the forces acting on the tool. The numerical results demonstrate that personal computers can today be used to model even most difficult cases of the CWR process, where complex shapes of tools and thermal phenomena occurring during forming are taken into consideration

Numerical analysis of the skew rolling process for main shafts

The paper discusses a new technique of skew rolling with three tapered rolls and its application to the production of long main shafts of steel that are used in light trucks. First, the design of this forming technique is described. Then the paper stresses the universality of this process, as the skew rolling technique enables forming various products using one set of rolls. The reported numerical results (workpiece shape change during rolling, maps of effective strains and temperatures as well as loads and torques) confirm that the discussed technique is suitable for producing long shafts

FEM Simulation of the Cross-Wedge Rolling Process for a Stepped Shaft

The paper presents the results of numerical modeling of a cross-wedge rolling process for producing a stepped shaft. The modeling was performed with commercial software Forge NxT 1.1 using the finite element method. The numerical analysis enabled the determination of changes in the shape of the workpiece, effective strain, damage function and temperature distributions, as well as variations in the forces and torque acting on the tool. The numerical results demonstrate that personal computers can today be used to model even the most difficult cases of the cross-wedge rolling process, in which complex shapes of the tools and thermal phenomena occurring during the forming process have to be taken into considerationПредставлены результаты численного моделирования процесса поперечно-клиновой прокатки для изготовления ступенчатого вала. Моделирование выполнялось на базе коммерческой программы Forge NxT 1.1 с использованием метода конечных элементов. Численное решение позволило определить изменения формы изделия, эффективной деформации, функции повреждаемости и распределения температур, а также сил и крутящих моментов, действующих на вал. Показано, что для моделирования даже наиболее трудных случаев процесса ПКП, когда необходимо учитывать сложные конфигурации изделий и тепловые явления, возникающие в процессе формоизменения, могут использоваться персональные компьютеры

Forming a lever preform made of aluminium alloy 2014

The paper presents the results of theoretical and experimental analyses of forge rolling for producing a lever preform made of aluminum alloy 2014. The forge rolling process was performed in an oval-circle rolling system. To verify the technological assumptions made, a comprehensive numerical analysis by finite element method was first performed, followed by experimental tests. The investigation demonstrated a high agreement between the numerical results and those obtained experimentally under real conditions. The numerical simulations allowed the determination of the distributions of strains, temperatures and normalized Cockcroft-Latham ductile fracture criterion

Experimental study of rotary compression for hollow parts

The paper describes rotary compression, a new method for producing hollow parts. First, a prototype machine fort his process is described. The machine was designed and constructed at the Lublin University of Technology. Next,selected experimental results of the rotary compression for hot worked hollow parts made of C45 steel are presented.The discussion of the results focuses on the effect of kinematic parameters on this forming process

Relationship Between Anti-DFS70 Autoantibodies and Oxidative Stress

Background: The anti-DFS70 autoantibodies are one of the most commonly and widely described agent of unknown clinical significance, frequently detected in healthy individuals. It is not known whether the DFS70 autoantibodies are protective or pathogenic. One of the factors suspected of inducing the formation of anti-DFS70 antibodies is increased oxidative stress. We evaluated the coexistence of anti-DFS70 antibodies with selected markers of oxidative stress and investigated whether these antibodies could be considered as indirect markers of oxidative stress. Methods: The intensity of oxidative stress was measured in all samples via indices of free-radical damage to lipids and proteins such as total oxidant status (TOS), concentrations of lipid hydroperoxides (LPH), lipofuscin (LPS), and malondialdehyde (MDA). The parameters of the non-enzymatic antioxidant system, such as total antioxidant status (TAS) and uric acid concentration (UA), were also measured, as well as the activity of superoxide dismutase (SOD). Based on TOS and TAS values, the oxidative stress index (OSI) was calculated. All samples were also tested with indirect immunofluorescence assay (IFA) and 357 samples were selected for direct monospecific anti DFS70 enzyme-linked immunosorbent assay (ELISA) testing. Results: The anti-DFS70 antibodies were confirmed by ELISA test in 21.29% of samples. Compared with anti-DFS70 negative samples we observed 23% lower concentration of LPH (P =.038) and 11% lower concentration of UA (P =.005). TOS was 20% lower (P =.014). The activity of SOD was up to 5% higher (P =.037). The Pearson correlation showed weak negative correlation for LPH, UA, and TOS and a weak positive correlation for SOD activity. Conclusion: In samples positive for the anti-DFS70 antibody a decreased level of oxidative stress was observed, especially in the case of samples with a high antibody titer. Anti-DFS70 antibodies can be considered as an indirect marker of reduced oxidative stress or a marker indicating the recent intensification of antioxidant processes

Analysis of the impact of sex and age on the variation in the prevalence of antinuclear autoantibodies in Polish population: a nationwide observational, cross-sectional study

The detection of antinuclear autoantibody (ANA) is dependent on many factors and varies between the populations. The aim of the study was first to assess the prevalence of ANA in the Polish adult population depending on age, sex and the cutoff threshold used for the results obtained. Second, we estimated the occurrence of individual types of ANA-staining patterns. We tested 1731 patient samples using commercially available IIFA using two cutoff thresholds of 1:100 and 1:160. We found ANA in 260 participants (15.0%), but the percentage of positive results strongly depended on the cutoff level. For a cutoff threshold 1:100, the positive population was 19.5% and for the 1:160 cutoff threshold, it was 11.7%. The most prevalent ANA-staining pattern was AC-2 Dense Fine speckled (50%), followed by AC-21 Reticular/AMA (14.38%) ANA more common in women (72%); 64% of ANA-positive patients were over 50 years of age. ANA prevalence in the Polish population is at a level observed in other highly developed countries and is more prevalent in women and elderly individuals. To reduce the number of positive results released, we suggest that Polish laboratories should set 1:160 as the cutoff threshold

Metal flow in twist drill extrusion with different friction factors

W artykule przedstawiono wyniki symulacji numerycznych procesu wyciskania współbieżnego wierteł krętych. Do badań wykorzystano oprogramowanie oparte na metodzie elementów skończonych DEFORM 3D. Symulacje numeryczne przeprowadzono dla różnych sił tarcia, których wielkość określano poprzez zmianę czynnika tarcia plastycznego. Na podstawie przeprowadzonych badań numerycznych prześledzono wpływ zmiennych parametrów tribologicznych na powierzchni kontaktu materiału kształtowanego i narzędzi na kinematykę płynięcia metalu podczas wyciskania elementów śrubowych. W wyniku wykonanych symulacji stwierdzono, że zwiększenie sił tarcia powoduje w przypadku wyciskania wierteł krętych wyrównanie gradientu prędkości płynięcia metalu. Ponadto przedstawiono uzyskane rozkłady odkształceń w wyrobach otrzymanych na drodze numerycznej symulacji oraz zestawiono parametry siłowe procesu dla rozpatrywanych przypadków.The paper presents the results of numerical simulations of the twist drill backward extrusion process. In the simulations, the FEM-based software DEFORM 3D was used. The numerical simulations were performed for various friction forces whose values were determined by changing the plastic friction factor. Based on the conducted numerical simulations, the effect of the variable tribological parameters of the contact surface between the material being formed and the tools on the kinematics of material flow in the extrusion process were investigated. In the effect of the performed simulations, it has been found that increasing the friction forces in a twist drill extrusion leads to the uniformity of the metal flow velocity gradient. Additionally, the strain distributions obtained in the simulations are presented and the force parameters in the investigated cases are compared

Forming of Hollow Shaft Forging From Titanium Alloy Ti6Al4V by Means of Rotary Compression

This paper presents chosen results of theoretical-experimental works concerning forming of hollow shafts forgings from titanium alloys, which are applied in aviation industry. At the first stage of conducted analysis, the forging forming process was modeled by means of finite element method. Calculations were made using software Simufact Forming. On the basis of performed simulations optimal parameters of rotary compression process were determined. Next, experimental tests of forging forming in laboratory conditions were made. For the research needs, a forging aggregate, designed by the Authors, was used. Conducted research works confirmed the possibility of metal forming (by means of rotary compression) of hollow shafts from hard workable titanium alloys. Numerous advantages of rotary compression process, make it attractive both for low series production (aircraft industry) and for mass production (automotive industry)