scholarly journals Spring-back effect during multi-pass bending of sheet blanks

2019 ◽  
Vol 135 ◽  
pp. 01066
Author(s):  
Volodymyr Kukhar ◽  
Mykyta Nahnibeda ◽  
Oleksii Radushev
Keyword(s):  
Experimental Research ◽  
Thickness Ratio ◽  
Basic Information ◽  
Spring Back ◽  
Bending Angle ◽  
The Difference ◽  
Geometric Quality ◽  
Back Angle ◽  
Number Of Passes

A significant factor, which leads to the discrepancy of the final sizes of the bent sheet parts to their drawings is the springing of the sheet blank during bending. At the same time, the springing during multi-pass bending is not sufficiently studied. The purpose of the work is to obtain the graphical and mathematical dependencies for descriptions of the resultative spring-back angle of the blanks at the multi-pass bending, taking into account the width of the blank, number of passes, and pre-bending angle at each preliminary pass. The paper describes the basic information about the difference between the spring-back angle for one-pass or multi-pass bending. In the course of the study it is shown that during calculations of forming and preventive prediction of the geometric quality of bending shapes it is necessary to take into account properties of the blank material, as well as the angles of the prebends and the width to thickness ratio of the blank. A methodology of experimental research was developed for determining the spring-back angle during multi-pass bending in three bending dies with 109°, 91° and 72° pass-by-pass reducing angles.

Study of NC Cold Tube Bending Spring-Back Characteristics

2010 ◽  
Vol 154-155 ◽  
pp. 202-208 ◽  
Author(s):  
Yi Nan Lai ◽  
Sheng Le Ren ◽  
Zeng Lou Li ◽  
Jun Tao Gu ◽  
Guang Fei Wu
Keyword(s):  
High Reliability ◽  
Prediction Equation ◽  
Strong Nonlinearity ◽  
Spring Back ◽  
Tube Bending ◽  
Bending Angle ◽  
Bending Process ◽  
Elasto Plasticity ◽  
Bending Radius ◽  
Back Angle

The unloading spring-back of tubes during its manufacturing process shows a strong nonlinearity, which greatly influences the precision of parts. In this paper, the strain distribution of bending tubes was analyzed based on the elasto-plasticity theory, and the theoretical equation for spring-back of tubes was derived. The numerical simulation model for cold tube-bending process was developed with prediction error of 9% compared with experimental results, indicating high reliability of the model. The 12Cr1MoV and 20G tubes were used to analyze the effects of bending angle, bending radius and bending speed on the spring-back of tubes. The prediction equation of spring-back was built, which shows that the spring-back tendency was in accordance with theoretical analysis results. The simulated results show that the spring-back angle is linearly proportional to the bending angle within a certain range. In addition, it is proportional to the relative bending radius and the bending speed.

Research of New Splitting Process of Pipe Billets from 2618A Aluminium Alloy Basing on Cross-Wedge Rolling

2013 ◽  
Vol 58 (3) ◽  
pp. 725-729 ◽  
Author(s):  
A. Tofil
Keyword(s):  
Aluminium Alloy ◽  
Experimental Research ◽  
Cross Wedge Rolling ◽  
Bending Angle ◽  
Precise Analysis ◽  
Rolling Method ◽  
Material Separation ◽  
Forming Angle ◽  
Splitting Process

Abstract This paper are presented the results of theoretical and experimental research on splitting without waste of pipe billets from aluminium alloy realized basing on cross-wedge rolling method. The analyzed process is connected with rolling of a V-shape groove on a split billet circumference, and later with rotary bending causing material separation. In theoretical analysis, based on simulations by means of finite element method, basic models of metal cracking (brittle and ductile) were applied. During calculations, the following process parameters were changed: forming angle α, bending angle θ and reduction ratio ∆r. The achieved results allowed for a precise analysis of the splitting process within the scope of: state of strain, kinematics of flow, force parameters, state of stresses and type of cracking of the split material. On the basis of experimental research, the influence of the analyzed parameters on the surface of splitting was estimated and scope of parameters guaranteeing the assumed quality of the product was given. The comparison of theoretical and experimental results showed good conformity.

scholarly journals Influencing Variables of Drawing Process using Magnesium Tubes

2019 ◽  
Vol 9 (2) ◽  
pp. 598-601
Keyword(s):  
Cross Section ◽  
Wall Thickness ◽  
Tube Wall ◽  
Drawing Process ◽  
Spring Back ◽  
Bending Angle ◽  
Tube Wall Thickness ◽  
The Cross ◽  
Back Angle ◽  
Thinning Rate

The present work examines the deformation of magnesium tubes using drawing process. During examination, absence of wrinkling and cracking is witnessed at 303k. The effect of mandrel on the cross section of the extruded tubes, wall thickness and spring-back of the bent tube are vividly discussed. Results show that presence of mandrel decreases the cross section of distortion and the spring back angle. Further, the present investigation clarifies the thinning rate of tube wall thickness. It is found that at the bending angle of 90° largest distortion is witnessed.

Letter to the Editor: The Continuing Challenge of Evaluating RSD Impairment and Disability

1998 ◽  
Vol 3 (5) ◽  
pp. 8-10
Author(s):  
Robert L. Knobler ◽  
Charles N. Brooks ◽  
Leon H. Ensalada ◽  
James B. Talmage ◽  
Christopher R. Brigham
Keyword(s):  
Disability Evaluation ◽  
Body Part ◽  
Loss Of Function ◽  
Regulatory Requirements ◽  
Major Cardiac Event ◽  
Clinical Scenarios ◽  
Impairment Score ◽  
Occupational Activities ◽  
The Difference

Abstract The author of the two-part article about evaluating reflex sympathetic dystrophy (RSD) responds to criticisms that a percentage impairment score may not adequately reflect the disability of an individual with RSD. The author highlights the importance of recognizing the difference between impairment and disability in the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides): impairment is the loss, loss of use, or derangement of any body part, system, or function; disability is a decrease in or the loss or absence of the capacity to meet personal, social, or occupational demands or to meet statutory or regulatory requirements because of an impairment. The disparity between impairment and disability can be encountered in diverse clinical scenarios. For example, a person's ability to resume occupational activities following a major cardiac event depends on medical, social, and psychological factors, but nonmedical factors appear to present the greatest impediment and many persons do not resume work despite significant improvements in functional capacity. A key requirement according to the AMA Guides is objective documentation, and the author agrees that when physicians consider the disability evaluation of people, more issues than those relating to the percentage loss of function should be considered. More study of the relationships among impairment, disability, and quality of life in patients with RSD are required.

COMBINATORIAL POLYNOMIALLY COMPUTABLE CHARACTERISTICS OF SUBSTITUTIONS AND THEIR PROPERTIES

2020 ◽  
Vol 7 (2) ◽  
pp. 34-41
Author(s):  
VLADIMIR NIKONOV ◽  
◽  
ANTON ZOBOV ◽  
Keyword(s):  
Mathematical Expectation ◽  
Point Of View ◽  
Small Range ◽  
Computational Point ◽  
Wide Range ◽  
Bijective Function ◽  
The Difference ◽  
Element Base ◽  
Selection Of

The construction and selection of a suitable bijective function, that is, substitution, is now becoming an important applied task, particularly for building block encryption systems. Many articles have suggested using different approaches to determining the quality of substitution, but most of them are highly computationally complex. The solution of this problem will significantly expand the range of methods for constructing and analyzing scheme in information protection systems. The purpose of research is to find easily measurable characteristics of substitutions, allowing to evaluate their quality, and also measures of the proximity of a particular substitutions to a random one, or its distance from it. For this purpose, several characteristics were proposed in this work: difference and polynomial, and their mathematical expectation was found, as well as variance for the difference characteristic. This allows us to make a conclusion about its quality by comparing the result of calculating the characteristic for a particular substitution with the calculated mathematical expectation. From a computational point of view, the thesises of the article are of exceptional interest due to the simplicity of the algorithm for quantifying the quality of bijective function substitutions. By its nature, the operation of calculating the difference characteristic carries out a simple summation of integer terms in a fixed and small range. Such an operation, both in the modern and in the prospective element base, is embedded in the logic of a wide range of functional elements, especially when implementing computational actions in the optical range, or on other carriers related to the field of nanotechnology.

Analysis of the influence of the hole depth on the geometric quality of the machined part, when the cutting fluid and the machining parameters are varied

2017 ◽  
Author(s):  
Eder Silva Costa ◽  
Pedro Henrique Pires França ◽  
Leonardo Rosa Ribeiro da Silva ◽  
Wisley Sales ◽  
Álisson Rocha Machado ◽  
...  
Keyword(s):  
Cutting Fluid ◽  
Machining Parameters ◽  
Hole Depth ◽  
Geometric Quality

THE INFLUENCE OF TILLAGE SYSTEMS ON THE GROWTH, DEVELOPMENT AND YIELD OF LONG-FLAX

2020 ◽  
Author(s):  
V. Dumych ◽  
Keyword(s):  
Growth And Development ◽  
Field Experiments ◽  
Conservation Tillage ◽  
Mineral Fertilizers ◽  
Tillage Systems ◽  
Yield And Quality ◽  
Tillage System ◽  
The Difference ◽  
Flax Seeds

The purpose of research: to improve the technology of growing flax in the Western region of Ukraine on the basis of the introduction of systems for minimizing tillage, which will increase the yield of trusts and seeds. Research methods: field, laboratory, visual and comparative calculation method. Research results: Field experiments included the study of three tillage systems (traditional, canning and mulching) and determining their impact on growth and development and yields of trusts and flax seeds. The traditional tillage system included the following operations: plowing with a reversible plow to a depth of 27 cm, cultivation with simultaneous harrowing and pre-sowing tillage. The conservation system is based on deep shelfless loosening of the soil and provided for chiseling to a depth of 40 cm, disking to a depth of 15 cm, cultivation with simultaneous harrowing, pre-sowing tillage. During the implementation of the mulching system, disking to a depth of 15 cm, cultivation with simultaneous harrowing and pre-sowing tillage with a combined unit was carried out. Tillage implements and machines were used to perform tillage operations: disc harrow BDVP-3,6, reversible plow PON-5/4, chisel PCh-3, cultivator KPSP-4, pre-sowing tillage unit LK-4. The SZ-3,6 ASTPA grain seeder was used for sowing long flax of the Kamenyar variety. Simultaneously with the sowing of flax seeds, local application of mineral fertilizers (nitroammophoska 2 c/ha) was carried out. The application of conservation tillage allows to obtain the yield of flax trust at the level of 3,5 t/ha, which is 0,4 t/ha (12.9 %) more than from the area of traditional tillage and 0,7 t/ha (25 %) in comparison with mulching. In the area with canning treatment, the seed yield was the highest and amounted to 0,64 t/ha. The difference between this option and traditional and mulching tillage reaches 0,06 t/ha (10,3 %) and 0.10 t/ha (18.5 %), respectively. Conclusions. Preservation tillage, which is based on shelf-free tillage to a depth of 40 cm and disking to a depth of 15 cm has a positive effect on plant growth and development, yield and quality of flax.

Pengaruh ovaprim, aromatase inhibitor, dan hipofisa terhadap kualitas telur ikan Lele Dumbo (Clarias gariepinus)

2017 ◽  
Vol 5 (1) ◽  
Author(s):  
Erwin A. Aziz ◽  
Ockstan Kalesaran
Keyword(s):  
Survival Rate ◽  
Experimental Design ◽  
Aromatase Inhibitor ◽  
Fish Larvae ◽  
Clarias Gariepinus ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
The Difference ◽  
Hatching Eggs

This study aimed to determine the effect of ovaprim hormone, aromatase inhibitor and pituitary on the quality of the catfish eggs (Clarias gariepinus). Experimental Design used was Completely Randomized Design (CRD) with four treatments, each with three replications. Treatment A: ovaprim; treatment B: Aromatase inhibitors, treatment C: hypophysis and treatment D: Control. The results showed that the difference in treatment gave highly significant effect on fertilization and hatching eggs but no significant effect on the survival rate of larvae. Aromatase inhibitor hormone was the best because it provided highly significant effect on fertilization (92.66%), hatchability of eggs (95%), and surviva rate (81.33%) of fish larvae.   Keywords : Clarias gariepinus. Ovaprim, Aromatase Inhibitor, Hypophysis, egg, larvae

Multivariate micropollutants analysis in marine waters

1995 ◽  
Vol 32 (9-10) ◽  
pp. 341-348
Author(s):  
V. Librando ◽  
G. Magazzù ◽  
A. Puglisi
Keyword(s):  
Multivariate Data Analysis ◽  
Partial Least Squares Regression ◽  
Environmental Chemistry ◽  
Sampling Site ◽  
Principal Component ◽  
Least Squares Regression ◽  
Organic Micropollutants ◽  
Suspended Material ◽  
The Difference

The monitoring of water quality today provides a great quantity of data consisting of the values of the parameters measured as a function of time. In the marine environment, and especially in the suspended material, increasing importance is being given to the presence of organic micropollutants, particularly since some are known to be carcinogenic. As the number of measured parameters increases examining the data and their consequent interpretation becomes more difficult. To overcome such difficulties, numerous chemometric techniques have been introduced in environmental chemistry, such as Multivariate Data Analysis (MVDA), Principal Component Analysis (PCA) and Partial Least Squares Regression (PLSR). The use of the first technique in this work has been applied to the interpretation of the quality of Augusta bay, by measuring the concentration of numerous organic micropollutants, together with the classical water pollution parameters, in different sites and at different times. The MVDA has highlighted the difference between various sampling sites whose data were initially thought to be similar. Furthermore, it has allowed a choice of more significant parameters for future monitoring and more suitable sampling site locations.

Non-steady variations of SOD and phosphate release rate due to changes in the quality of the overlying water

2000 ◽  
Vol 42 (3-4) ◽  
pp. 265-272 ◽  
Author(s):  
T. Inoue ◽  
Y. Nakamura ◽  
Y. Adachi
Keyword(s):  
Release Rate ◽  
Oxygen Demand ◽  
Phosphate Concentration ◽  
Sediment Oxygen Demand ◽  
Biochemical Reactions ◽  
Overlying Water ◽  
Phosphate Release ◽  
Do Concentration ◽  
The Difference

A dynamic model, which predicts non-steady variations in the sediment oxygen demand (SOD) and phosphate release rate, has been designed. This theoretical model consists of three diffusion equations with biochemical reactions for dissolved oxygen (DO), phosphate and ferrous iron. According to this model, step changes in the DO concentration and flow velocity produce drastic changes in the SOD and phosphate release rate within 10 minutes. The vigorous response of the SOD and phosphate release rate is caused by the difference in the time scale of diffusion in the water boundary layer and that of the biochemical reactions in the sediment. Secondly, a negative phosphate transfer from water to sediment can even occur under aerobic conditions. This is caused by the decrease in phosphate concentration in the aerobic layer due to adsorption.

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