scholarly journals Parametric effects in the frictional interaction of a tool with a billet in the process of its treatment by pressure

2019 ◽  
pp. 17-30
Author(s):  
A. D. Uchitel ◽  
Yu. A. Malinovskyi ◽  
G. V. Danilina ◽  
N. V. Voytenko ◽  
D. P. Rybak ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Metal Forming ◽  
Surface Layers ◽  
Operating Modes ◽  
Parametric Effects ◽  
Shaping Tool ◽  
Parametric Oscillations ◽  
Cold Metal ◽  
Periodic Components

Purpose. Justification of the influence of pulsating dynamic loads in the surface layers of parts obtained by plastic deformation methods on the quality of finished products during cold rolling, knurling, running in, drawing and stamping. Research methodology. A schematization was adopted in which the workpiece or part is an anisotropic medium elastically bonded along the surface of the junction of external reinforced layers with the internal mass of the part. On the basis of the proposed physical model, conditions were found under which under the action of cyclic surface loads, violations of the integrity of the appearance of fracturing and waviness of external fibers in the process of strengthening the treatment of semi-finished products and parts are possible. Findings. The obtained data allows us to establish the frequency characteristics of the process of unstable parametric oscillations caused by nonlinear friction between the forming element and the workpiece (part), which lead to a deterioration in the quality of finished products. In addition, for the steady-state operating modes of machines for cold metal forming, the dependence of the amplitudes of deformation waves, as functions of the maximum pulsations of the “periodic” components of surface forces, was obtained, and measures were proposed to reduce vibroactivity in the area of tool interaction with the workpiece and machine parts for cold processing. Originality. It consists in formulating and solving the second dynamic problem for the surface layers of the workpiece at the interface of the processed layers and the workpiece array. Depending on the occurring periodic forces for the surface layers, the conditions of steady and unstable operation of the shaping tool and the whole machine for metal forming by pressure, as a whole, are determined. Practical value of the work lies in the fact that safe modes of operation of metal forming machines have been identified, conditions for improving the design of machines for cold metal forming have been created, under which the possibility of occurrence of parametric oscillations, as well as the reduction of vibratory activity of machines for cold metal forming in minimized whole. Keywords: running in, knurling, drawing, plastic deformation, roller, tool, workpiece, the amplitude of oscillations, load, excitation coefficient, steady amplitude, deformation wave.

scholarly journals Justification of the effect of transitional modes on the quality of ready-made products when their treatment is used by plastic deformation methods from the position of the wave and auto vibration processes

2019 ◽  
pp. 6-16
Author(s):  
A. D. Uchitel ◽  
Yu. A. Malinovskyi ◽  
A. N. Panchenko ◽  
G. V. Danilina ◽  
S. Yu. Datsenko
Keyword(s):  
Plastic Deformation ◽  
Metal Forming ◽  
Dynamic Instability ◽  
Longitudinal Force ◽  
Elastic Base ◽  
Surface Layers ◽  
Tangential Forces ◽  
Definition Of

Purpose. Substantiation of the role of longitudinal and transverse wave processes in the surface layers on the quality of finished products obtained by plastic deformation methods, such as cold rolling, stamping, running in, drawing and others. Research methodology. In the work, to describe the transients at the beginning of the interaction of the tool with the workpiece, a computational model was applied in which the surface layers of the workpiece are represented as a beam on an elastic base, loaded with suddenly applied tangential forces, often exceeding their critical values. The reasons for the occurrence of unstable dynamic states of such a beam, in which the integrity of the surface layers of the workpiece and parts may be disturbed due to the occurrence of supercritical stresses and deformation in the material of the outer layers, are investigated. Findings. The results were obtained on the definition of hazardous states of the surface layers of the workpiece, under the action of suddenly applied loads at the initial moments of the capture of the workpiece, as well as at the moments when the tool slips over the workpiece during the alignment of their speeds. Originality. It consists in the fact that the first dynamic problem was set and solved for the surface layers of the workpiece, represented as a two-support beam on an elastic base loaded with a suddenly applied longitudinal force, which can significantly exceed its critical value. Denoted areas of dynamic instability of the surface layers of the workpiece. The practical value of the work lies in the fact that the modes of operation of the metal forming machine and the parameters of the workpiece were identified under which conditions for obtaining products of insufficient quality may arise. As well as developed recommendations for improving the quality of finished products. Key words: metal forming, transients, longitudinal wave, shear wave, billet, loaded layer, overload coefficient, dynamic buckling, tool, rolling, knurling, drawing, hypothetical beam, impact, elastic wave propagation velocity.

scholarly journals FEM analysis of the plastic deformation of the regular arched asperities in the two-stage cold metal forming processes

2019 ◽  
Author(s):  
Leon Kukielka ◽  
Lukasz Bohdal ◽  
Jaroslaw Chodor ◽  
Katarzyna Gotowala ◽  
Pawel Kaldunski ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Metal Forming ◽  
Fem Analysis ◽  
Two Stage ◽  
Cold Metal

Characterization of lubricants for metal forming by means of an oscillating tribo-test-rig

2009 ◽  
Vol 223 (5) ◽  
pp. 817-826 ◽  
Author(s):  
C Monetti ◽  
S Ilo ◽  
T Lebersorger
Keyword(s):  
Metal Forming ◽  
Testing System ◽  
Test Rig ◽  
Efficient Technology ◽  
Load Range ◽  
Quality Of Products ◽  
Cold Metal ◽  
Increasing Load

Cold metal forming is a versatile and very efficient technology in the manufacture of metal components. In cold metal forming processes high pressure is generated at the tool-workpiece interface, so that good lubrication is required to reduce wear. This improves tool life and the quality of products. The lubricants used in the forming processes usually contain appropriate basis oils with anti-wear (AW) and extreme pressure (EP) additives. In order to examine how wear occurs during cold metal forming, the SRV (Schwingung Reibung Verschleiss) reciprocating-sliding tribometer equipped with a cylinder-on-disc line- contact testing system was adapted and used to characterize lubricant behaviour. Friction coefficient and wear rate were determined under progressively increasing load conditions. The final worn volumes of the flat and the cylinder were evaluated by using optical microscopy methods. The measurement system was validated by replicate tests using some commercially available forming lubricants as reference in a load range of 100-1000 N. The oscillating tribo-test-rig can be used to characterize lubricants for cold metal forming processes by testing the combined effects of different additive systems and their interaction with contacting materials.

scholarly journals BACKGROUND TO THE ARRANGEMENT OF AUTOMATING AND VOLVOUS PROCESSES IN THE FORM-FORMING MACHINES WHEN TREATING THE PREPARATIONS AND DETAILS BY THE PLASTIC DEFORMATION METHOD

2018 ◽  
pp. 21-29
Author(s):  
A.D. Uchitel ◽  
Yu.A. Malinovsky ◽  
A.N. Panchenko ◽  
G.V. Danilina ◽  
S.Y. Datsenko
Keyword(s):  
Plastic Deformation ◽  
Friction Pair ◽  
Slip Rate ◽  
Cold Plastic Deformation ◽  
Deformation Wave ◽  
Surface Layers ◽  
Deformation Method ◽  
Dynamic Background ◽  
Variable Friction ◽  
Shaping Tool

Purpose. Analysis of surface-hardening technology for cold processing of metals, taking into account the deformation-wave processes occurring in the area in front of the shaping tool. Methodology. To establish the reasons for obtaining finished products with increased roughness, insufficient contact strength, fracturing and peeling of the surface layers, as well as the occurrence of significant dynamic loads in the mechanisms of machines for machining parts using plastic deformation, a two-mass design model is used in which the working tool is connected by friction with the moving processed workpiece. Findings. The results of determining the conditions for the occurrence of self-oscillations in the system “workpiece - tool” are presented. Based on the analysis of the friction characteristics as a function of the mutual slip rate between the workpiece and the shaping tool, the range of slip speeds is set, at which the self-oscillating processes for the friction pair can be excited: "tool - workpiece". Originality consists in the fact that the influence of the variable friction force on the occurrence of sustained self-oscillations between the workpiece being processed and the tool in the machines for “cold” plastic deformation of the metal has been established. The conditions for the occurrence and absence of self-oscillations in the zone of contact between the tool and the workpiece are found. Practical value lies in the fact that the modes of operation of machines for processing products by plastic deformation have been revealed under which unregulated roughness, fracturing and “peeling” of the parts being machined can occur, as well as a high dynamic background during the operation of the shaping tool of driving and power mechanisms. Practical recommendations are given to improve the performance of finished products and reduce vibroactivity in the drive. Keywords: running in, dragging, knurling, plastic deformation, elastic deformation wave, roller, tool, blank.

Modification of tundish design to improve quality of slabs, casted at CCM No. 4 of EVRAZ NTMK

2020 ◽  
Vol 76 (6) ◽  
pp. 559-563
Author(s):  
I. M. Zakharov ◽  
V. A. Smirnov ◽  
D. V. Sushnikov ◽  
A. G. Lyzhin ◽  
E. A. Lavrova ◽  
...  
Keyword(s):  
Basic Number ◽  
Metal Level ◽  
Surface Layers ◽  
Secondary Oxidation ◽  
Strip Rolling ◽  
Actual Distribution ◽  
Ultrasonic Control ◽  
Analysis Of Results ◽  
Water Simulation

A technology of continuous casting of steel has a large effect on its contamination. In particular, proper organization of metal flows in tundish and mold is very important. After completion a series of casting through a tundish and drop of metal level in it, it possible, that the slag flows from the surface layers of the tundish to capture the metal. An analysis of results of ultrasonic control of finished strip showed, that the basic number of the revealed defects was obtained during strip rolling out of the last slabs of the last heat in a series for a tundish. Metallographic studies determined, that the defects were located in the slab axis zone and filled by macro-inclusions of complex composition. To determine the actual distribution of metal flows, a water simulation of them was accomplished for the existing design of the EVRAZ NTMK tundish. It was determined, that at the drop of metal level in a tundish, a capture of slag from the metal reservoir and its transfer into the main bath of the tundish takes place due to whirligig flows. Following the weight metal consumption, the zone of slag inclusions distribution enlarges. Besides, denudation of the metal mirror in the metal reservoir takes place, resulted in metal secondary oxidation. Based on the results of the simulation, it was proposed to modify the design of the “turbostop”, which is installed in the metal reservoir of the tundish. Besides, it was proposed to remove the dividers installation in the tundish. It was noted, that the proposed steps enable to ensure a minimal level of rejections.

Soft Reduction of a Cast Ingot on the Incomplete Crystallization Stage

2013 ◽  
Vol 762 ◽  
pp. 261-265 ◽  
Author(s):  
Tanya I. Cherkashina ◽  
Igor Mazur ◽  
Sergey A. Aksenov
Keyword(s):  
Metal Forming ◽  
Physical Simulation ◽  
Fluid Layer ◽  
Liquid Core ◽  
Soft Reduction ◽  
Deformation Processes ◽  
Novel Method ◽  
Full Scale Tests ◽  
Crystallization Stage

Numerical and physical simulation on model samples can provide data for various aspects of metal forming, without resorting to time-consuming and costly full-scale tests. This paper presents examples of modeling of the deformation of a slab with a liquid core. The use of soft reduction can enhance the homogeneity of the structure, which improves the quality of cast billets. Mathematical modeling is described here where the fluid layer is taken into account by the influence of boundary conditions in the crust in the form of ferrostatic pressure, which allows calculation of the intensity of deformation, total deformation and strain. It also provides a novel method for studying the process of soft reduction. It is based on a physical model of the slab consisting of a closed solid shell made of a calibrated lead shot and the Wood's alloy. To simulate the liquid molten metal, the interior of the shell is filled with gelatin. This approach can be applied to further studies on deformation processes and the penetration of deformation into complex metallic systems.

Formability of Explosive Welded Mg/Al Bimetallic Bar

2016 ◽  
Vol 716 ◽  
pp. 114-120 ◽  
Author(s):  
Sebastian Mróz ◽  
Piotr Szota ◽  
Teresa Bajor ◽  
Andrzej Stefanik
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Process Parameters ◽  
Metal Forming ◽  
Explosive Welding ◽  
Physical Modelling ◽  
Main Process ◽  
Compression Tests ◽  
Welding Method

The paper presents the results of physical modelling of the plastic deformation of the Mg/Al bimetallic specimens using the Gleeble 3800 simulator. The plastic deformation of Mg/Al bimetal specimens characterized by the diameter to thickness ratio equal to 1 was tested in compression tests. The aim of this work was determination of the range of parameters as temperature and strain rate that mainly influence on the plastic deformation of Mg/Al bars during metal forming processes. The tests were carried out for temperature range from 300 to 400°C for different strain rate values. The stock was round 22.5 mm-diameter with an Al layer share of 28% Mg/Al bars that had been produced using the explosive welding method. Based on the analysis of the obtained testing results it has been found that one of the main process parameters influencing the plastic deformation the bimetal components is the initial stock temperature and strain rate values.

scholarly journals Physical model of «substrate-coating» system structuring in complex modification processes of surface layers in working parts of dies and press molds

2018 ◽  
Vol 2018 (11) ◽  
pp. 35-41
Author(s):  
Олег Морозов ◽  
Oleg Morozov ◽  
Валерий Кокорин ◽  
Valeriy Kokorin ◽  
Владимир Табаков ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Physical Model ◽  
Cold Plastic Deformation ◽  
Coating System ◽  
Resistant Steel ◽  
Surface Layers ◽  
Heat Resistant Steel ◽  
Plasma Sputtering ◽  
Ion Plasma ◽  
Wear Coatings

Basic methods to increase durability of die working parts including processes of cold plastic deformation at anti-wear coatings application by a method of ion-plasma sputtering are considered. A physical model of cold plastic deformation of samples made of heat-resistant steel H12M is presented.

scholarly journals Common defects of parts manufactured through single point incremental forming

2021 ◽  
Vol 343 ◽  
pp. 04007
Author(s):  
Mihai Popp ◽  
Gabriela Rusu ◽  
Sever-Gabriel Racz ◽  
Valentin Oleksik
Keyword(s):  
Sheet Metal ◽  
Metal Forming ◽  
Incremental Forming ◽  
Single Point ◽  
Single Point Incremental Forming ◽  
Forming Process ◽  
Metal Forming Process ◽  
Serial Robot ◽  
The Many ◽  
Cold Metal

Single point incremental forming is one of the most intensely researched die-less manufacturing process. This process implies the usage of a CNC equipment or a serial robot which deforms a sheet metal with the help of a relatively simple tool that follows an imposed toolpath. As every cold metal forming process, besides the many given advantages it has also some drawbacks. One big drawback in comparison with other cold metal forming processes is the low accuracy of the deformed parts. The aim of this research is to investigate the sheet metal bending mechanism through finite element method analysis. The results shows that the shape of the retaining rings has a big influence over the final geometrical accuracy of the parts manufactured through single point incremental forming.

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