scholarly journals SUBSTANTIATION OF CHIPPING FRACTURE MECHANICS DURING DRAWING OF CYLINDRICAL SURFACES WITH ALLOWANCE

2020 ◽  
pp. 73-84
Author(s):  
Yuriy Paladiychuk ◽  
Vasyl Kordonsky
Keyword(s):  
Chip Formation ◽  
Complex Problem ◽  
Preliminary Deformation ◽  
Profile Angle ◽  
Processed Material ◽  
Relative Shear ◽  
Chip Shrinkage ◽  
Deformation Hardening ◽  
Deformed State ◽  
Minimum Depth

The mechanics of chip fracture when cutting the allowance of pre-divisible technological grooves was studied for the first time, and the relationship between the profile and depth of the latter and the characteristics of the stress-strain state in the chip formation zone (relative shear, chip shrinkage, shear angle, front angle, contact processes . This article discusses a more complex problem - the longitudinal division of chips or allowance. Most researchers are inclined to believe that this problem should be solved by pre-dividing the allowance by a network of special chip-splitting ring or screw grooves. The depth of these grooves should be 0.6… 0.95 of the amount of rise on a single tooth of the broach. The results of the study of the mechanics of chip destruction are described when the tool meets the process groove in the drawing process. The connection between the structure of the pipe and the intensively deformed state in the zone of chip formation is shown. From the obtained results the following follows. Preliminary deformation hardening by means of deforming drawing allows to increase hardness of OM twice (steel 10), to 60% (steel 35), to 50% (steel 45) and to 25% (aluminum alloy AK6). This significantly reduces the shrinkage coefficient of chips (respectively 2; 1.4; 1.4 and 1.3 times) and the actual previous angle (at a sharpening angle γ = 15⁰, respectively: from 36⁰ to 18⁰; from 25⁰ to 17⁰; from 21⁰ to 16⁰ and from 22⁰ to 17⁰). All this indicates a decrease in the intensity of the cutting process with increasing intensity of the previous HPD The following minimum values of the groove profile angle for the investigated materials 2φmin were determined: 80⁰ (steel10); 60⁰ (steel 35); 50⁰ (steel 45 and alloy AK6). It is established that the minimum depth of the chip-splitting groove hC is determined from the condition of chip destruction when the tangential stresses in the shear zone are exceeded above the shear resistance of the processed material. The following values of the minimum depth of the chip-splitting groove for the studied materials were obtained: hCmin = (0.4… 0.55) Sz - steels 35 and 45; hCmin = (0.55 (0.6) Sz - AK6 alloy.

scholarly journals Impact of cutting face profile angle upon shear deformation degree

2017 ◽  
Vol 2 (6) ◽  
pp. 14-20 ◽  
Author(s):  
Александр Ямников ◽  
Aleksandr Yamnikov ◽  
Дмитрий Волков ◽  
Dmitry Volkov
Keyword(s):  
Shear Deformation ◽  
Metal Cutting ◽  
Cutting Tools ◽  
Deformation Degree ◽  
Thread Cutting ◽  
Profile Angle ◽  
Chip Flow ◽  
Relative Shear ◽  
Definition Of ◽  
The Impact

It is established that cutting with gear-cutting and thread-cutting tools is not free that results in the increase of loading upon tool tips and their quick wear. The layers of metal cut are subjected to considerable shear deformation and also to other kinds of deformation. In this connection the wear character of a tool and its properties will change. There is considered a process of chip removal by trapezoidal and triangular cutters (as in case of metal cutting off with teeth of a hob may be used not three but two tool tips) and the impact of a cutting face profile angle upon a shear deformation degree is also considered. There are shown analytical dependences for the definition of angles of a chip flow, a relative shear, a deformation degree of a shear and a value of tangential stresses in the cutting area taking into account the influence of the strength of material machined, width and thickness of a layer cut and a friction factor. The dependences are checked up at cutting with a trapezoidal cutter.

Research of stamping of unequal channel bars. Part 4. Deformed state of the workpiece when extruding channels. 1. Deformations in the area of wall formation

2021 ◽  
pp. 44-49
Author(s):  
A.L. Vorontsov
Keyword(s):  
Plastic Deformation ◽  
Plane Deformation ◽  
Wall Formation ◽  
Die Forging ◽  
Deformation Hardening ◽  
Deformed State ◽  
Accumulated Deformation

Determination of the deformed state of the workpiece at free extrusion of channels is considered. Formulas are obtained that make it possible to determine the accumulated deformations at a given point of the center of plastic deformation and the extruded walls of the product for any working stroke of the punch. Keywords: die forging, extrusion, misalignment, punch, matrix, plane deformation, accumulated deformation, hardening. [email protected]

scholarly journals CHIP FORMATION DURING THERMAL FRICTION TURN-MILLING

2020 ◽  
pp. 1-6
Author(s):  
Karibek Sherov
Keyword(s):  
Chip Formation ◽  
Cutting Speed ◽  
Shrinkage Factor ◽  
Root Area ◽  
Metallographic Method ◽  
30Khgsa Steel ◽  
Chip Shrinkage ◽  
Turn Milling ◽  
Shrinkage Coefficient

This paper presents the results of chip formation studies in the processing of 30KhGSA steel by thermofriction turn-milling. When studying the process in this work there are presented the results of studying chip formation when the processing of chip formation there is used the metallographic method. Chip root area investigated. The dependence of the chip shrinkage coefficient on the cutting speed and feed was also investigated. It is established that with increasing supply S the value of the chip shrinkage coefficient K decreases. The higher the chip shrinkage factor, the more work will be required to cut the chips and the more complex the processing process.

scholarly journals DETAILS’ REPAIR OF CONSTRUCTION AND ROAD MACHINES: FLUCTUATIONS’ MODELLING

2019 ◽  
Vol 16 (5) ◽  
pp. 534-542
Author(s):  
V. E. Ovsyannikov ◽  
V. I. Vasilyev
Keyword(s):  
Chip Formation ◽  
Vibration Amplitude ◽  
Geometrical Parameters ◽  
Double Support ◽  
Processed Material ◽  
Productivity Increase ◽  
Definition Of ◽  
The Impact ◽  
Cutting Modes ◽  
Oscillatory Processes

Introduction. Hole details are quite widely used in structures of construction and road machines. The specialists apply boring for draft, semi-fair, and in some cases for fair processing of such surfaces. This type of processing is often followed by the negative nature of oscillatory processes that leads to decrease in accuracy and in the surface quality. The paper studies the possibility of the calculation method’s usage in oscillatory processes, which allows assigning the cutting modes by providing required output parameters.Materials and methods. The authors used the double-support beam as a design model of a boring cutter. The solution of the fluctuations’ modeling came down to definition of point movements, which corresponded to cutter top (points of application equally effective cutting forces). The authors made the definition of movements with use of Mor integrals. Therefore, the paper considered the impact of chip formation and separation due to perturbing forces.Results. The authors carried out the calculation of forces’ values in cutting with use of the degree dependences. Moreover, the authors accepted the formation’s frequency as the frequency of the perturbing influenced structure. The frequency of the chip formation was defined on the basis of estimated dependences, which connected parameters of the tool, the cut-off layer and modes of cutting. As a result, the author received the implementations of oscillatory processes and studied the influence of different factors on vibration amplitude.Discussion and conclusions. The authors make assessment of the received results’ adequacy by comparison with experimental data. The error doesn’t exceed 20%. The developed model considers geometrical parameters of the tool (a departure, plate corners, etc.), the modes of cutting both mechanical properties of the processed material and parameters of the chip formation. The model can be used both at design of boring operations and by optimization of the cutting modes for the purpose of productivity increase.

Nuclear Processes Related to the Ap Stars and the Heaviest Chemical Elements

1976 ◽  
Vol 32 ◽  
pp. 169-182
Author(s):  
B. Kuchowicz
Keyword(s):  
Nuclear Physics ◽  
Nuclear Reactions ◽  
Chemical Elements ◽  
Fission Products ◽  
Abundance Pattern ◽  
Isotopic Shifts ◽  
Processed Material ◽  
R Process ◽  
Ap Stars ◽  
Nuclear Processes

SummaryIsotopic shifts in the lines of the heavy elements in Ap stars, and the characteristic abundance pattern of these elements point to the fact that we are observing mainly the products of rapid neutron capture. The peculiar A stars may be treated as the show windows for the products of a recent r-process in their neighbourhood. This process can be located either in Supernovae exploding in a binary system in which the present Ap stars were secondaries, or in Supernovae exploding in young clusters. Secondary processes, e.g. spontaneous fission or nuclear reactions with highly abundant fission products, may occur further with the r-processed material in the surface of the Ap stars. The role of these stars to the theory of nucleosynthesis and to nuclear physics is emphasized.

Complex Problem Solving and Worked Examples

2009 ◽  
Vol 23 (2) ◽  
pp. 129-138 ◽  
Author(s):  
Florian Schmidt-Weigand ◽  
Martin Hänze ◽  
Rita Wodzinski
Keyword(s):  
Problem Solving ◽  
Cognitive Load ◽  
Learning Experience ◽  
Worked Examples ◽  
Complex Problem ◽  
Complex Problem Solving ◽  
Strategic Learning ◽  
Learning Behavior ◽  
Worked Example ◽  
8Th Grade

How can worked examples be enhanced to promote complex problem solving? N = 92 students of the 8th grade attended in pairs to a physics problem. Problem solving was supported by (a) a worked example given as a whole, (b) a worked example presented incrementally (i.e. only one solution step at a time), or (c) a worked example presented incrementally and accompanied by strategic prompts. In groups (b) and (c) students self-regulated when to attend to the next solution step. In group (c) each solution step was preceded by a prompt that suggested strategic learning behavior (e.g. note taking, sketching, communicating with the learning partner, etc.). Prompts and solution steps were given on separate sheets. The study revealed that incremental presentation lead to a better learning experience (higher feeling of competence, lower cognitive load) compared to a conventional presentation of the worked example. However, only if additional strategic learning behavior was prompted, students remembered the solution more correctly and reproduced more solution steps.

The Prediction of Problem-Solving Assessed Via Microworlds

2016 ◽  
Vol 32 (4) ◽  
pp. 298-306 ◽  
Author(s):  
Samuel Greiff ◽  
Katarina Krkovic ◽  
Jarkko Hautamäki
Keyword(s):  
Working Memory ◽  
Problem Solving ◽  
Complex Problem ◽  
Two Dimensions ◽  
Assessment Instruments ◽  
Complex Problem Solving ◽  
Visual Spatial ◽  
Rule Knowledge ◽  
Rule Application ◽  
Fluid Reasoning

Abstract. In this study, we explored the network of relations between fluid reasoning, working memory, and the two dimensions of complex problem solving, rule knowledge and rule application. In doing so, we replicated the recent study by Bühner, Kröner, and Ziegler (2008) and the structural relations investigated therein [ Bühner, Kröner, & Ziegler, (2008) . Working memory, visual-spatial intelligence and their relationship to problem-solving. Intelligence, 36, 672–680]. However, in the present study, we used different assessment instruments by employing assessments of figural, numerical, and verbal fluid reasoning, an assessment of numerical working memory, and a complex problem solving assessment using the MicroDYN approach. In a sample of N = 2,029 Finnish sixth-grade students of which 328 students took the numerical working memory assessment, the findings diverged substantially from the results reported by Bühner et al. Importantly, in the present study, fluid reasoning was the main source of variation for rule knowledge and rule application, and working memory contributed only a little added value. Albeit generally in line with previously conducted research on the relation between complex problem solving and other cognitive abilities, these findings directly contrast the results of Bühner et al. (2008) who reported that only working memory was a source of variation in complex problem solving, whereas fluid reasoning was not. Explanations for the different patterns of results are sought, and implications for the use of assessment instruments and for research on interindividual differences in complex problem solving are discussed.

Measurement of erosion state and refractory lining thickness of blast furnace hearth by using three-dimensional laser scanning method

2020 ◽  
Vol 118 (1) ◽  
pp. 106
Author(s):  
Lei Zhang ◽  
Jianliang Zhang ◽  
Kexin Jiao ◽  
Guoli Jia ◽  
Jian Gong ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Laser Scanning ◽  
Refractory Lining ◽  
Three Dimensional ◽  
3D Laser Scanning ◽  
Scanning Method ◽  
Blast Furnace Production ◽  
Severe Erosion ◽  
Residual Thickness ◽  
Minimum Depth

The three-dimensional (3D) model of erosion state of blast furnace (BF) hearth was obtained by using 3D laser scanning method. The thickness of refractory lining can be measured anywhere and the erosion curves were extracted both in the circumferential and height directions to analyze the erosion characteristics. The results show that the most eroded positions located below 20# tuyere with an elevation of 7700 mm and below 24#–25# tuyere with an elevation of 8100 mm, the residual thickness here is only 295 mm. In the circumferential directions, the serious eroded areas located between every two tapholes while the taphole areas were protected well by the bonding material. In the height directions, the severe erosion areas located between the elevation of 7600 mm to 8200 mm. According to the calculation, the minimum depth to ensure the deadman floats in the hearth is 2581 mm, corresponding to the elevation of 7619 mm. It can be considered that during the blast furnace production process, the deadman has been sinking to the bottom of BF hearth and the erosion areas gradually formed at the root of deadman.

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