INVESTIGATION OF THE PROCESS OF RESTORATION OF DAMAGED PIPELINE SURFACES BY THE METHOD OF SURFACE RIVETING

2021 ◽  
pp. 126-132
Author(s):  
О.В. Уразов ◽  
А.Д. Данилов
Keyword(s):  
Residual Stress ◽  
Work Hardening ◽  
Experimental Studies ◽  
Surface Plastic Deformation ◽  
Numerical Control ◽  
Surface Plastic ◽  
Machined Surface ◽  
Surface Work ◽  
Stress Components ◽  
Industrial Unit

Представлены результаты экспериментальных исследований процесса восстановления поврежденных поверхностей трубопроводов различных диаметров методом поверхностного наклепа, реализующего явление поверхностного пластического деформирования, приводящее к изменению распределения напряжений по толщине, выполнено обоснование оптимальных режимов его проведения . При этом было осуществлено численное моделирование процесса накатки, определены оптимальные значения следующих параметров: глубины и силы ППД, скорости ППД, подачи ролика, формы рабочей поверхности используемого ролика. При анализе были учтены следующие физико-механические характеристики: глубина наклепа, величина остаточных напряжений, глубина распределения остаточных напряжений, время обкатки, нагрузка на ролик. Доказано очевидное преимущество роликов большего радиуса профиля - они позволяют обеспечить необходимое изменение шероховатости обрабатываемой поверхности при обкатке с большей подачей, что приводит к снижению времени технологического процесса. При этом в принятом диапазоне параметров режимов обкатки (нагрузка 2500÷3000Н, глубина вдавливания 0.04÷0.06мм) величины компонентов остаточных напряжений оказались практически идентичными для исследованных режимов всех рассмотренных роликов. Полученные результаты были положены в основу технологии восстановительного ремонта трубопроводов различного диаметра без остановки производственного процесса на Нововоронежской АЭС и создана промышленная установка с числовым программным управлением для реализации данной технологии Here we present the results of experimental studies of the process of restoration of damaged surfaces of pipelines of various diameters by the method of surface work hardening, which implements the phenomenon of surface plastic deformation, leading to a change in the distribution of stresses along the thickness. At the same time, we carried out a numerical simulation of the knurling process, we determined the optimal values of the following parameters: the depth and strength of the SPD, the speed of the SPD, the feed of the roller, the shape of the working surface of the roller used. The analysis took into account the following physical and mechanical characteristics: work hardening depth, residual stress value, residual stress distribution depth, running time, roller load. We proved the obvious advantage of rollers with a larger profile radius - they allow one to provide the necessary change in the roughness of the machined surface during rolling with a higher feed, which leads to a decrease in the time of the technological process. In this case, in the accepted range of parameters of the running modes (load 2500-3000N, indentation depth 0.04-0.06 mm), the values of the residual stress components turned out to be almost identical for the considered modes for all the considered rollers. We used the results as the basis for the technology of restorative repair of pipelines of various diameters without stopping the production process at the Novovoronezh NPP and an industrial unit with numerical control was created to implement this technology

Investigation on Machined Surface Quality During Cutting of GH4169 Under High-Pressure Cooling

2020 ◽  
Vol 12 (7) ◽  
pp. 994-1003
Author(s):  
Ming-Yang Wu ◽  
Wei-Xu Chu ◽  
Ke-Ke Liu ◽  
Shu-Jie Wu ◽  
Yao-Nan Cheng
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
High Pressure ◽  
Tensile Stress ◽  
Surface Quality ◽  
Work Hardening ◽  
Surface Plastic ◽  
Residual Tensile Stress ◽  
Machined Surface ◽  
Machined Surface Quality

The aerospace component material GH4169 has low thermal conductivity and poor machinability, resulting in difficulty to guarantee good surface quality after conventional cutting. High-pressure cooling assisted machining technology can effectively improve the problem. In order to study the effect of high-pressure cooling assisted processing technology on the machined surface quality of GH4169, in this paper, Deform-3D was first used to construct a thermo-mechanical coupling finite element model for turning GH4169 under high-pressure cooling conditions, to analyze the turning temperature and surface residual stress. Then, analysis was carried out on the residual stress, work hardening behavior, and metamorphic layer of the GH4169 machined surface, in combination with the turning experiment. The results show that, under the conditions of little feeding and highspeed cutting, the GH4169 turning surface generates residual tensile stress along with both the feeding and turning directions. Moreover, the residual tensile stress gradually turns into the residual compressive stress along the depth direction. The application of high-pressure coolant can reduce the residual tensile stress of the machined surface. As the cooling pressure increases, the residual tensile stress of the machined surface decreases. The coupling effect between thermal deformation and plastic deformation when turning GH4169 can cause the work hardening of the surface, and the hardening degree decreases with the increase of cooling pressure. The high-pressure cooling assisted machining technology can effectively reduce surface plastic deformation, and promote the lessening of grain refinement degree of the material surface, thereby reducing the thickness of the metamorphic layer.

The Machined Surface Residual Stress of Nano-Ceramics with Two-Dimensional Ultrasonic Vibration Assisted Grinding

2010 ◽  
Vol 455 ◽  
pp. 637-642 ◽  
Author(s):  
X.Q. Zhang ◽  
Chong Yang Zhao ◽  
Bao Yu Du
Keyword(s):  
Residual Stress ◽  
Ultrasonic Vibration ◽  
Wear Particle ◽  
Surface Plastic Deformation ◽  
Work Piece ◽  
Surface Plastic ◽  
Two Dimensional ◽  
Surface Residual Stress ◽  
Machined Surface ◽  
Ultrasonic Grinding

Surface plastic deformation form and residual stress distribution of nano-ceramics machined by ordinary grinding and two-dimensional ultrasonic grinding respectively were investigated. The obtained results show that machined surface residual stress in the two grinding modes is extrusion stress, and it decreased with the increasing of grinding depth. But the decrease of residual stress under two-dimensional ultrasonic grinding is less than that under normal grinding. In addition, under the same grinding parameters, the surface residual stress on two-dimensional ultrasonic vibration grinding is larger than that on ordinary grinding, and if other parameters unchanged, it is increased with the increase of wear particle granularity in the two grinding modes. It is produced by the reason that ductile regime of ceramic grinding become larger under ultrasonic grinding, so that material is still removed by plastic form at great depth. Plastic removal mode will produce greater surface extrusion stress, so with the increasing of grinding depth, the decreasing of residual stress under two-dimensional ultrasonic vibration grinding is less than that under the normal grinding. At the same time, the regular separating between wear particle and work piece improves the heat emission condition, which is also one of the reasons that the surface residual stress under two-dimensional ultrasonic grinding is larger than that under ordinary grinding.

Plastic deformation of collector plates at electric motor repair

2020 ◽  
pp. 79-82
Author(s):  
D.YU. Belan ◽  
G.B. Toder ◽  
K.V. Averkov ◽  
YU.V. Titov
Keyword(s):  
Plastic Deformation ◽  
Electric Motor ◽  
Roughness Parameter ◽  
Surface Plastic Deformation ◽  
Analytical Dependence ◽  
Surface Plastic ◽  
Machined Surface ◽  
Tool Surface ◽  
Diamond Burnishing ◽  
Traction Electric Motor

A tool was developed for smoothing the plates of an electric motor collector. An analytical dependence of the roughness parameter of the machined surface on the force applied to the tool is obtained. Keywords traction electric motor, collector, diamond burnishing tool, surface-plastic deformation, repair, roughness. [email protected]

scholarly journals INCREASING THE EFFICIENCY OF SURFACE STRENGTHENING OF METAL PRODUCTS BY COMBINED THERMODEFORMATION PROCESSING

2020 ◽  
pp. 103-110
Author(s):  
Oleksandr Danyleiko ◽  
Vitaliy Dzhemelinskyi ◽  
Dmytro Lesyk ◽  
Artemii Bernatskyi
Keyword(s):  
Surface Layer ◽  
Laser Beam ◽  
Surface Hardening ◽  
Thermal Deformation ◽  
Experimental Studies ◽  
Numerical Control ◽  
Surface Plastic ◽  
Beam Diameter ◽  
Metal Products ◽  
Deformation Surface

The article discusses the prospects of using combined thermal deformation surface processing to improve the performance properties of metal products. There is a new method of thermal deformation surface hardening (shot peening (SP) followed by laser heat treatment (LHT)) for tools and crown housings operating under difficult conditions proposed. For carrying out experimental studies, flat samples of 30KhGSA steel and steel 45 were selected. Preliminary hardening and finishing with static or dynamic methods of surface plastic deformation were carried out on a modernized installation based on a DYNAMITE 2800 numerical control machine, and SP was implemented on industrial equipment. Laser surface hardening of the samples was carried out in single passes with a sample moving speed of 300...500 mm/min with a laser beam diameter of 7.3 mm and a laser power of 1 kW using the ROFIN-SINAR DY 044 technological unit. The optimal regimes of surface hardening are determined under the deformation action of a gas-dynamic flow with solid particles and thermal action by a laser beam to obtain maximum values ​​of hardening depth and hardness. In particular, with SP, the gas-feed stream feed pressure is 0.5 MPa, the processing time is 1 min, regardless of the type of material. The optimal laser beam power is 1 kW at a sample travel speed of 300 mm/min. There are the results of experimental studies of the change in the hardening depth as a function of time and pressure after SP, the speed of movement of the treated sample from carbon steel 45 and medium alloyed steel 30KhGSA after LHT and combined SP+LHT, and also the distribution of microhardness over the depth of the hardened layer presented. It is revealed that the combined SP+LHT of 30 KhGSA steel at optimal modes forms 1.5 times (1.3 mm) greater depth of the strengthened surface layer in comparison with LHT, while providing the surface layer hardness of ~5400 MPa.

Influence of Cutting Speed on Surface Plastic Deformation and White Layer Formation of FGH95

2013 ◽  
Vol 589-590 ◽  
pp. 70-75 ◽  
Author(s):  
Jin Du ◽  
Zhan Qiang Liu
Keyword(s):  
Plastic Deformation ◽  
Surface Integrity ◽  
White Layer ◽  
High Reliability ◽  
Cutting Speed ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Layer Formation ◽  
Machined Surface ◽  
White Layer Formation

The superalloy parts in the aeronautical field demand high reliability, which is largely related to surface integrity. Surface integrity generally includes three parameters, such as geometric parameter, mechanical parameter and metallurgical parameter. The paper presents the influence of cutting speed on surface plastic deformation and white layer formation through orthogonal milling of FGH95 superally material. The influence of cutting speed on grain refinement of machined surface is also investigated. It is found that cutting speed has significantly effect on the surface metallurgical characteristic microstructure. The increasing of cutting speed creates severer plastic deformation. Surface plastic shear strain increases with the increasing of cutting speed, while the depth of plastic deformation decreases on contrary. White layer thickness is increased with the increasing of cutting speed. Through statistical analysis for grains number, it can be drawn that the higher the cutting speed, the more serious grains refinement.

Study of Surface Layer Hardening after Treatment Complex Tool

2020 ◽  
Vol 303 ◽  
pp. 89-96
Author(s):  
K.S. Mitrofanova
Keyword(s):  
Plastic Deformation ◽  
Surface Layer ◽  
Strain State ◽  
Experimental Studies ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Technological Inheritance ◽  
Multiple Loading ◽  
Surface Layer Hardening ◽  
Solidified Body

The results of experimental studies of the thin surface layer of samples made of steel 45 after treatment with surface plastic deformation (SPD) multiradius roller (MR-roller) are presented. On the basis of the apparatus of the mechanics of technological inheritance, taking into account the effect of the solidified body, a model of the process according to the scheme of multiple loading-unloading of metal, taking into account the phenomenology of the SPD process and the properties of the material, is created. Distributions of parameters of the stress-strain state in the deformation centre are obtained, the parameters of roughness and microhardness of the surface layer are investigated.

Using the Simplex Design Technique for Optimization of Modes of Burnishing with Ball Tools

2018 ◽  
Vol 284 ◽  
pp. 1210-1214
Author(s):  
A.V. Tyurin ◽  
N.Ya. Galimova ◽  
A.V. Belyaev
Keyword(s):  
Plastic Deformation ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Initial Surface ◽  
Design Technique ◽  
High Quality ◽  
Machined Surface ◽  
Damping Effect ◽  
Simplex Design ◽  
Variable Factor

It is advantageous to use the method of surface plastic deformation in order to get high-quality surfaces that meet increased requirements for strength and reliability. For efficient process of surface plastic deformation, it is required to define a set of conditions to provide minimum roughness of a machined surface. The paper addresses the problem of experimental search of optimal burnishing modes using the simplex design to minimize roughness of a machined surface. The significance of variable factor ranking was observed for this technique. A specific set of tests resulted in decrease in the initial surface roughness almost by 15 times in the specimens made of aluminum alloy after burnishing with the steel indenter. It was established that the surface quality was significantly affected by a new factor – angle of indenter contact with the machined surface, which had a damping effect on the machine-fixture-tool-workpiece system. The experiments showed that polished indenter balls significantly lowered the roughness grade of the machined surface under the same conditions.

scholarly journals Effect of Machined Surface Integrity on Fatigue Performance of Metal Workpiece: A Review

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Guoliang Liu ◽  
Chuanzhen Huang ◽  
Bin Zhao ◽  
Wei Wang ◽  
Shufeng Sun
Keyword(s):  
Residual Stress ◽  
Surface Topography ◽  
Surface Integrity ◽  
Work Hardening ◽  
Fatigue Cracks ◽  
Fatigue Performance ◽  
Effective Control ◽  
Published Data ◽  
Machined Surface ◽  
Machined Surface Integrity

AbstractFatigue performance is a serious concern for mechanical components subject to cyclical stresses, particularly where safety is paramount. The fatigue performance of components relies closely on their surface integrity because the fatigue cracks generally initiate from free surfaces. This paper reviewed the published data, which addressed the effects of machined surface integrity on the fatigue performance of metal workpieces. Limitations in existing studies and the future directions in anti-fatigue manufacturing field were proposed. The remarkable surface topography (e.g., low roughness and few local defects and inclusions) and large compressive residual stress are beneficial to fatigue performance. However, the indicators that describe the effects of surface topography and residual stress accurately need further study and exploration. The effect of residual stress relaxation under cycle loadings needs to be precisely modeled precisely. The effect of work hardening on fatigue performance had two aspects. Work hardening could increase the material yield strength, thereby delaying crack nucleation. However, increased brittleness could accelerate crack propagation. Thus, finding the effective control mechanism and method of work hardening is urgently needed to enhance the fatigue performance of machined components. The machining-induced metallurgical structure changes, such as white layer, grain refinement, dislocation, and martensitic transformation affect the fatigue performance of a workpiece significantly. However, the unified and exact conclusion needs to be investigated deeply. Finally, different surface integrity factors had complicated reciprocal effects on fatigue performance. As such, studying the comprehensive influence of surface integrity further and establishing the reliable prediction model of workpiece fatigue performance are meaningful for improving reliability of components and reducing test cost.

Surface Integrity and Fatigue Property of a High Speed Milled Titanium Alloy

2008 ◽  
Vol 53-54 ◽  
pp. 305-310 ◽  
Author(s):  
Guo Sheng Geng ◽  
Jiu Hua Xu
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Titanium Alloy ◽  
Surface Integrity ◽  
Work Hardening ◽  
High Speed ◽  
Cutting Speed ◽  
Fatigue Property ◽  
Machined Surface ◽  
Metallurgical Structure

Surface integrity has a great effect on the fatigue property of titanium alloy. The surface integrity and fatigue property of a high speed milled Ti-6.5Al-2Zr-1Mo-1V (TA15) titanium alloy were investigated in this research. The main objective of this paper is to study the influence of milling speed on the surface integraty and fatigue property of the machined part. The surface roughness, work hardening, metallurgical structure and residual stress of the machined surface were studied in a cutting speed range of from 50m/min to 300m/min. To verify the relationship between cutting speed and the surface integrity of machined surface, the fatigue property of titanium alloy specimens milled at four different cutting speeds ranging from 50 to 200m/min were compared at two stress levels. This research shows that the cutting speed has little effect on the work hardening, metallurgical structure and residual stress, but the surface roughness decreases with the increasing cutting speed. Therefore, increasing milling speed has a positive effect on the surface integrity and fatigue property of the machined surface.

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