Features of the Heating Process in Ultrasonic Welding of Polycarbonate Products under Independent Pressure

2020 ◽  
pp. 54-62
Author(s):  
S.S. Volkov ◽  
A.L. Remizov ◽  
A.S. Pankratov
Keyword(s):  
Welded Joints ◽  
Welded Joint ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Heating Process ◽  
Mechanism Of Formation ◽  
High Quality ◽  
Acoustic Contact ◽  
Welding Pressure

This paper presents a mechanism of formation of a hard-to-weld polycarbonate joint by ultrasonic welding. The method utilizes internal and external friction occurring in the welded joint area on abutting surfaces due to shear vibrations of the end of the upper part relative to the lower part. A layer of the heated welded material is formed, localized by thickness, in which predominant absorption of the ultrasonic vibrations occurs, which allows one to obtain high-quality and durable welded joints without significant deformation due to the concentration of thermal energy in the welding zone. The effect of independent welding pressure on the strength of the welded joint of polycarbonate is considered. A new method of ultrasonic welding under the conditions of independent pressure is proposed. The method consists of dividing the static welding pressure into two components: the pressure of the acoustic contact in the zone of contact of the waveguide with the product, and the welding pressure that compresses the welded products, with the latter component being lower than the former. In order to obtain high-quality welded joints made of polycarbonate and to prevent displacement of the welded edges during the welding process relative to each other, a special preparation of the welded edges is developed, which allows one part to be moved vertically relative to the other during the welding process. It is established that the quality of welding depends on the speed of movement and the angle of cutting the edges.

scholarly journals The Influence of Technological Parameters on Durability of Products from ABS Plastic at Ultrasonic Welding

2019 ◽  
pp. 17-26
Author(s):  
S.S. Volkov ◽  
S.A. Korolev ◽  
D.S. Rozanov
Keyword(s):  
Welded Joint ◽  
Oscillation Amplitude ◽  
Heat Removal ◽  
Amplitude Distribution ◽  
Ultrasonic Welding ◽  
Optimal Choice ◽  
Welding Parameters ◽  
Technological Parameters ◽  
Welding Pressure

An ultrasonic welding method for round-shaped products made from ABS plastic is described in this paper. This method can eliminate roughness and waviness on the contact surface between the planimetric waveguide and the welded part, increase heat removal from the surface of the welded part in the subwaveguide zone and improve the efficiency of ultrasonic welding as well as the strength and quality of the welded joint. It is shown that a mushroom-shaped waveguide is the optimal choice for planimetric ultrasonic welding of ABS parts of the fan wheel type with regard to the uniformity of the oscillation amplitude distribution along the perimeter of the waveguide’s working end face. The optimal form of the waveguide’s working end face is defined that entails fixing the connecting parts relative to the waveguide’s axis along their diameter. It is established that at a certain combination of the ultrasonic welding modes for ABS plastic the rate of deformation at large welding pressures can turn out to be higher than at small pressures. This is caused by the competition of three factors: temperatures, static welding pressure and concentration of energy on the welded surfaces. It is determined that for welding ABS plastic the so-called soft modes of ultrasonic welding with small static welding pressure and oscillation amplitude of the waveguide’s end face should be used. In this case welding occurs only due to the distribution of microroughness, without dents from the waveguide on the surface of the welded material. Optimal welding parameters for ABS plastic are determined.

Evaluation of Influence of Thermal Methods of Metal Separation Cutting on Welding Quality

2017 ◽  
Vol 265 ◽  
pp. 755-761 ◽  
Author(s):  
A.K. Tingaev ◽  
M.A. Ivanov ◽  
A.M. Ulanov
Keyword(s):  
Heat Affected Zone ◽  
Welded Joints ◽  
Heat Input ◽  
Experimental Studies ◽  
Welding Process ◽  
Regulatory Requirements ◽  
High Quality ◽  
Thermal Methods ◽  
Welding Seam

We have investigated a possibility of obtaining high-quality welded joints after oxygen and plasma cutting of steel С355 without removing the heat-affected zone (HAZ), in which the changes in chemical, phase and structural compositions are observed. Numerical and experimental studies of the effect of heat input of MAG and Submerged Arc welding on the quality of welded joints are performed. In particular, it was found that when the heat input of welding is at least 6.5 kJ/cm, the metal of HAZ of the edges after cutting is heated during the welding to temperatures above Ас3, which leads to its full recrystallization. When the heat input of welding is at least 10 kJ/cm, the edges after cutting are completely melted and become a part of the welding seam metal. The presence of extensive areas of melting and recrystallization of the edges in the welding process contributes to obtaining high-quality welded joints without removing the HAZ of the edges after cutting. To verify the results of numerical studies, experimental tests of control welded joints were conducted, which showed that the values of bending angle and impact toughness of the welding seam metal and heat affected zone are significantly above the regulatory requirements to quality of welded joints, and not less than the same requirements for steel С355. The obtained results confirm the possibility of revising domestic regulatory requirements for the steel constructions production in terms of the preparation of edges for welding using technologies of thermal cutting without subsequent machining.

Analysis of Quality of Welded Joints of Iron-Concrete Products

2019 ◽  
Vol 942 ◽  
pp. 121-130 ◽  
Author(s):  
Ludmila Redko ◽  
Inna Plotnikova ◽  
Nataliya Chicherina ◽  
Olga Tchaikovskaja ◽  
Josefa Bastida
Keyword(s):  
Economic Development ◽  
Life Cycle ◽  
Statistical Methods ◽  
Welded Joints ◽  
Failure Modes ◽  
Welding Process ◽  
Negative Effects ◽  
High Quality ◽  
Welded Structures

The search for effective methods of management is one of the strategic directions of economic development. To obtain high-quality products, organizations should manage nonconformities and causes of product defects. The paper focuses on the analysis of groups of defects of welded joints using statistical methods. Welding process was considered as one of the processes of management. The possible causes of nonconformities were indicated. The method of failure modes and effects analysis was used to quantify the level of risk. A matrix of consequences and probabilities was presented, and critical risks and risk situations were selected. The proposed measures to eliminate or minimize negative effects enable identification of problem areas of the life cycle of welded structures.

Features of structure formation processes in AA2024 alloy joints formed by the friction stir welding with bobbin tool

2021 ◽  
Vol 23 (2) ◽  
pp. 98-115
Author(s):  
Alexey Ivanov ◽  
◽  
Valery Rubtsov ◽  
Andrey Chumaevskii ◽  
Kseniya Osipovich ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Structure Formation ◽  
Welded Joints ◽  
Heat Input ◽  
Welded Joint ◽  
Welding Process ◽  
Tool Material ◽  
Travel Speed ◽  
Material System ◽  
Friction Stir

Introduction. One of friction stir welding types is the bobbin friction stir welding (BFSW) process, which allows to obtain welded joints in various configurations without using a substrate and axial embedding force, as well as to reduce heat loss and temperature gradient across the welded material thickness. This makes the BFSW process effective for welding aluminum alloys, which properties are determined by their structural-phase state. According to research data, the temperature and strain rate of the welded material have some value intervals in which strong defect-free joints are formed. At the same time, much less attention has been paid to the mechanisms of structure formation in the BFSW process. Therefore, to solve the problem of obtaining defect-free and strong welded joints by BFSW, an extended understanding of the basic mechanisms of structure formation in the welding process is required. The aim of this work is to research the mechanisms of structure formation in welded joint of AA2024 alloy obtained by bobbin tool friction stir welding with variation of the welding speed. Results and discussion. Weld formation conditions during BFSW process are determined by heat input into a welded material, its fragmentation and plastic flow around the welding tool, which depend on the ratio of tool rotation speed and tool travel speed. Mechanisms of joint formation are based on a combination of equally important processes of adhesive interaction in “tool-material” system and extrusion of metal into the region behind the welding tool. Combined with heat dissipation conditions and the configuration of the “tool-material” system, this leads to material extrusion from a welded joint and its decompaction. This results in formation of extended defects. Increasing in tool travel speed reduce the specific heat input, but in case of extended joints welding an amount of heat released in joint increases because of specific heat removal conditions. As a result, the conditions of adhesion interaction and extrusion processes change, which leads either to the growth of existing defects or to the formation of new ones. Taking into account the complexity of mechanisms of structure formation in joint obtained by BFSW, an obtaining of defect-free joints implies a necessary usage of various nondestructive testing methods in combination with an adaptive control of technological parameters directly in course of a welding process.

scholarly journals Contributions Regarding the Use of Mechanical Vibrations in Order to Improve the Properties of Steels and Welded Joints Used in Metal Constructions

2020 ◽  
Vol 21 (2) ◽  
pp. 67-71
Author(s):  
Gheorghe Novac ◽  
Bogdan Novac
Keyword(s):  
Welded Joints ◽  
Arc Welding ◽  
Significant Contribution ◽  
Welding Process ◽  
Internal Stresses ◽  
Welding Equipment ◽  
Welding Technology ◽  
Submerged Arc ◽  
Very High

The paper presents aspects regarding the influence of vibrations on the mechanical properties of welded joints, made with basic materials of Spanish and Romanian origin. In this research is presented the practical way to make the necessary assemblies for the proposed tests. The tests show that vibrations have a significant contribution to the quality of welded joints. This is explained by the appearance of several crystallization centres which makes the structure finer. By using vibrations, the atoms are rearranged in the structure, ensuring a proper de-tensioning. The stresses induced in welded metals are significantly reduced by the use of vibration during welding process. The addition materials have a significant contribution to the emergence of stresses in welded joints as well. These stresses can contribute to the appearance of microstructural constituents with significant hardness. The welding equipment and technologies used also have a significant contribution to the emergence of the remaining stresses. For example, the submerged arc welding technology (SAF) can introduce very high internal stresses. By using vibrations during the welding process, it is achieved a fine structure and a significant reduction of remaining stresses in the welded joints.

scholarly journals Laser Welding Of Finned Tubes Made Of Austenitic Steels

2015 ◽  
Vol 60 (3) ◽  
pp. 1807-1812
Author(s):  
M. Stolecki ◽  
H. Bijok ◽  
Ł. Kowal ◽  
J. Adamiec
Keyword(s):  
Laser Welding ◽  
Austenitic Steel ◽  
Technological Process ◽  
Welded Joints ◽  
Austenitic Steels ◽  
Tube Production ◽  
High Quality ◽  
Manufacturing Costs ◽  
Finned Tubes

Abstract This paper describes the technology of welding of finned tubes made of the X5CrNi1810 (1.4301) austenitic steel, developed at Energoinstal SA, allowing one to get high quality joints that meet the requirements of the classification societies (PN-EN 15614), and at the same time to significantly reduce the manufacturing costs. The authors described an automatic technological line equipped with a Trumph disc laser and a tube production technological process. To assess the quality of the joints, one performed metallographic examinations, hardness measurements and a technological attempt to rupture the fin. Analysis of the results proved that the laser-welded finned tubes were performed correctly and that the welded joints had shown no imperfections.

scholarly journals Preliminary Research on Influence of Welding Parameters Strength at Welded Joints in Ribbed Reinforcing Steel

2020 ◽  
Vol 14 (3) ◽  
pp. 369-374
Author(s):  
Željko Bilić ◽  
Ivan Samardžić ◽  
Nedjeljko Mišina ◽  
Katarina Stoić
Keyword(s):  
Welded Joint ◽  
Welding Process ◽  
Welding Parameters ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Butt Welding ◽  
Control Interface ◽  
High Level ◽  
Non Destructive

As already known, no proper control or process control parameter which absolutely guarantees a high level quality of joints made by electro-resistive welding has been established so far, especially when all possible parameters are taken into account during the welding process. Due to the process of butt-welding being very short-lived, ensuring quality of the joints is a difficult and under-researched problem. The application of non-destructive testing methods to the control interface joints is also not reliable. Therefore, further research in this area should concentrate on studying the influence of basic welding parameters, and calculating their direct or indirect impact can serve to achieve a highquality welded joint with for practice sufficient accuracy.

scholarly journals Influence of welding method on microstructural creation of welded joints  

2011 ◽  
Vol 57 (Special Issue) ◽  
pp. S50-S56 ◽  
Author(s):  
P. Čičo ◽  
D. Kalincová ◽  
M. Kotus
Keyword(s):  
Welded Joints ◽  
Arc Welding ◽  
Welded Joint ◽  
Gas Metal Arc Welding ◽  
Structural Phase ◽  
Welding Parameters ◽  
Welding Method ◽  
Welding Technology ◽  
Metal Arc Welding

This paper is focused on the analysis of the welding technology influence on the microstructure production and quality of the welded joint. Steel of class STN 41 1375 was selected for the experiment, the samples were welded by arc welding including two methods: a manual one by coated electrode and gas metal arc welding method. Macro and microstructural analyses of the experimental welded joints confirmed that the welding parameters affected the welded joint structure in terms of the grain size and character of the structural phase.

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