Theoretical substantiation of reverse isothermal extrusion scheme of pipe billet with active friction and drawing of its edge part

2020 ◽  
pp. 540-543
Author(s):  
A.A. Pasynkov ◽  
S.N. Larin ◽  
A.N. Isaeva
Keyword(s):  
Stress State ◽  
Extrusion Process ◽  
Friction Forces ◽  
Theoretical Substantiation ◽  
Tube Billet ◽  
Active Friction ◽  
Edge Part ◽  
Simultaneous Use ◽  
Isothermal Extrusion

Method consisting in the implementation of the reverse extrusion process of tube billet in isothermal сondition of stamping with active friction is considered. Feature of the method is the simultaneous use of friction forces and pushing of the formed thickened edge part of the workpiece and its further straightening. The force conditions and stress state in the product are estimated. Comparison of this method with the classical extrusion scheme is given.

Effect of active action friction forces on technological parameters of backward extrusion

2021 ◽  
pp. 25-33
Author(s):  
B.S. Moroz ◽  
M.G. Dudnik
Keyword(s):  
Extrusion Process ◽  
Technological Parameters ◽  
Deformation Degree ◽  
Friction Forces ◽  
Backward Extrusion ◽  
Deformation Force ◽  
Active Friction Forces ◽  
The Impact ◽  
Experimental Researches ◽  
Experimental And Theoretical Studies

The parameters of deformation degree at theoretical and experimental researches of cold backward extrusion processes of hollow glasses-type products are considered. The dependences of their relationship with the relative degree of deformation and the scale of their conformity are suggested. The published results of experimental and theoretical studies on the impact of technological parameters of the backward extrusion process of hollow products in the conditions of active friction forces to reduce the deformation force and stress-strain state of the billet are analyzed. Insuffi ciently studied features of the process and the possibility for expanding of the application fi eld of the backward extrusion method with the active action of friction forces are noted. The method for calculating of the deformation rate required to determine the current stress in the implementation of the hot backward extrusion process.

scholarly journals A Cold-Pressing Method Combining Axial and Shear Flow of Powder Compaction to Produce High-Density Iron Parts

Technologies ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 70 ◽  
Author(s):  
Grigoriev ◽  
Dmitriev ◽  
Korobova ◽  
Fedorov
Keyword(s):  
Material Flow ◽  
Axial Loading ◽  
Powder Compaction ◽  
Friction Forces ◽  
Pressing Method ◽  
Cold Pressing ◽  
Traditional Design ◽  
Active Friction ◽  
Set Up ◽  
Active Friction Forces

Highly performance methods for cold pressing (cold die forging) of preforms from iron powder with subsequent heat treatment and producing ready parts made of powder are described in the paper. These methods allow fabricating parts with smooth surfaces and improved mechanical characteristics—porosity, tensile strength. Application of the traditional design set-up with a single-axial loading is restricted to high stresses in the dies to deform the preforms that lead to cracks formation. New powder compaction schemes by applying active friction forces (shear-enhanced compaction) make it possible to unload dies and produce high-quality parts by cold pressing. The scheme allows moving the die in the direction of the material flow with a velocity that exceeds the material flow velocity.

METHODOLOGY FOR CALCULATING THE STRESS STATE OF THE PILLAR FOR THE SALVAGE CHAMBER IN THE PRESENCE OF AN ADJACENT MINED OUT LONGWALL

2021 ◽  
Vol 4 (1) ◽  
pp. 364-374
Author(s):  
I. A. Ermakova ◽  
◽  
V. A. Fedusov
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress State ◽  
Quantitative Assessment ◽  
Underground Mines ◽  
The Finite Element Method ◽  
Load Factors ◽  
Relevant Task ◽  
Mining Conditions ◽  
Edge Part

Analysis of salvage operations at the underground mines of JSC SUEK-Kuzbass has shown that they can have different locations relative to the previously mined out adjacent longwall, which has a significant impact on the duration of salvage operations. If there is a previously mined out adjacent longwall next to the salvage chamber, the duration of salvage operations increases significantly, in contrast to the case when the salvage chamber is located within a pillar, outside the zone affected by the previously mined out longwall. In this regard, the calculation of the stress state of the pillar for the salvage chamber in the presence of an ad-jacent previously mined out longwall is a relevant task. The paper presents a methodology for quantitative assessment of the stress affecting the pillar for the salvage chamber, based on the use of the finite element method. An example of calculating the stress on the pillar for the sal-vage chamber in the presence of an adjacent mined out longwall for specific geological and mining conditions is considered. It has been established that the presence of a previously mined out adjacent longwall causes additional load on the specified pillar. The highest load factors are observed in the edge part of the pillar near the ventilation gateroad.

Temperature Evolution and Optimization of Hot Extrusion Process for Al-Zn-Mg-Cu Aluminium Alloy Based on FEM Simulation

2012 ◽  
Vol 166-169 ◽  
pp. 896-901
Author(s):  
Lei Xu ◽  
Guang Ze Dai ◽  
Xing Min Huang ◽  
Jun Wen Zhao ◽  
Jing Han ◽  
...  
Keyword(s):  
Stress State ◽  
Fem Simulation ◽  
Hot Extrusion ◽  
Extrusion Process ◽  
Maximum Temperature ◽  
Tension Stress ◽  
Incipient Melting ◽  
Extrusion Speed ◽  
Cu Alloy ◽  
The Right

Hot extrusion process of Al-Zn-Mg-Cu alloy billet had been simulated under different temperature of billet and container. It was proposed that due to large deformation and friction, maximum temperature of the billet occurs on the skin near extrusion export and is under three direction tension stress state, where surface is likely to crack if temperature surpassed the incipient melting point. The right temperature of the billet and container is 425°C~450°C and 400°C respectively with the constant extrusion speed 0.8mm/s

scholarly journals FORMATION OF QUALITATIVE INDICATORS OF PRODUCTS BY ROLLING STAMPING PROCESSES

2021 ◽  
pp. 75-83
Author(s):  
Viktor Matviychuk ◽  
Mykola Kolisnyk
Keyword(s):  
Wall Thickness ◽  
Relative Difference ◽  
Workpiece Material ◽  
Friction Forces ◽  
Utilization Factor ◽  
Service Characteristics ◽  
Metal Stamping ◽  
Active Friction ◽  
Deformation Kinematics ◽  
Active Friction Forces

The influence of rolling stamping on the service characteristics of products is investigated in the work. Based on the analysis of deformation kinematics, stress-strain state, microstructure and evaluation of deformability of workpiece material, ways to increase geometric accuracy, vacuum tightness, electrolytic stability and mechanical characteristics of product material, as well as ways to improve the material of workpieces for their subsequent processing. The influence of active friction forces on the nature of the material flow during SHO was established, which contributed to the development of new processes that allow to bring the shape and dimensions of the workpiece as close as possible to the finished part. Thus accuracy of the sizes of details corresponds to 7-11th qualities of accuracy, and roughness of the processed surfaces makes Ra = 2,5… 0,63 microns. The process of reshaping the square billets into round ones by the method of SHO is effective, which increases the utilization factor of the metal and reduces the anisotropy of its mechanical properties. The characteristic of flat anisotropy λr, adopted in sheet metal stamping as a characteristic of the ability of the material to form scallops, decreases as a result of reshaping by 70-80%. The relative difference in yield strength in the plane of the sheet decreases from 0.10-0.15 to 0.03-0.05. The ultimate tensile strain increases by 8-10%, and the uniform uniform strain - by 5-8%. This improvement in the characteristics of the material reshaped by rolling blanks leads to the fact that when drawing cylindrical products, the value of scallops decreases by 2-2.5 times, and the value of the maximum degree of drawing increases by 10-15%. This reduces the relative difference in wall thickness along the perimeter of the elongated workpiece, and the change in wall thickness along its height becomes linear. Thus, the use of SHO processes significantly improves the quality characteristics of products.

scholarly journals Finite Element Method Study on Stress State in Soil Induced by Agricultural Traffic

2016 ◽  
Vol 73 (2) ◽  
pp. 275
Author(s):  
Adrian Molnar-Irimie
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress State ◽  
Soil Compaction ◽  
Crop Production ◽  
Physical And Mechanical Properties ◽  
Inflation Pressure ◽  
Friction Forces ◽  
Soil Particles ◽  
Element Method

In general, when a tyre is running on a deformable soil, the soil compaction will occur not only on surface layers, but also on soil profile, in deeper layers. This leads to a series of negative effects not only on physical and mechanical properties of soil, but also influences the crops growth and the crop yield. For these reasons, currently are needed solutions to reduce soil compaction, caused mainly by agricultural implements passing on the soil surface in order to aply the specific crop production technologies. From our simulation we can draw the following conclusions: the soil stresses decreased with depth; the soil displacements magnitude increased with soil water content due to lower friction forces between soil particles (water acts like a lubricant between soil particles); decreasing rate for soil displacement is influenced by load magnitude and tyre inflation pressure; the soil particles moved in vertical plain from the top to the bottom, but also in horizontal direction, from the center to the edge in cross section and in longitudinal direction; the dimensions of the geometric shape of the mentioned soil volume is influenced by load and tyre inflation pressure. In this paper the agricultural traffic and its influence on stress state in soil, it was used a software application based on Finite Element Method, that has been proved to be a useful tool for soil compaction assessment in order to find the right decisions for a proper field traffic management.

Hot Extrusion of Thin-Wall Multichannel Copper Profiles

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Frank F. Kraft ◽  
Jonathan Kochis
Keyword(s):  
Heat Exchangers ◽  
High Efficiency ◽  
Hot Extrusion ◽  
Cold Drawing ◽  
Extrusion Process ◽  
Thin Wall ◽  
Channel Design ◽  
Extrusion Dies ◽  
Computer Controlled ◽  
Isothermal Extrusion

This paper presents the development of a unique, net shape, hot-extrusion process to produce precision, thin-wall, multichannel copper profiles for high efficiency heat-exchangers. This process is a departure from conventional copper extrusion, which is a nonisothermal process used primarily to produce simple semifinished products and hollow profiles requiring cold drawing after hot extrusion. A lab-scale apparatus was developed to simultaneously extrude multiple heated billets through a porthole type hollow die to form the multi-channel profiles. The process is performed at 700–750 °C, essentially at isothermal extrusion conditions. Temperature and tooling strength considerations necessitated the use of superalloys for the apparatus (which included dies, container, ram stems, and support tooling). A 250 kN computer controlled servo-hydraulic MTS® machine was used to provide the extrusion ram force. Two part designs were extruded to demonstrate process feasibility and versatility. A two-channel design with 0.2 mm wall thicknesses and an 11-channel design with wall-thicknesses of 0.3 mm were extruded. The extrusion ratios for these profiles are 67 and 25, respectively. Experimental data and an approach to analytically model the process are presented. Because solid-state welds in the tube walls are necessitated by the use of hollow extrusion dies, the microstructure in these regions is also presented.

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