Effects of Surface Profiles on the Joint Formation during Magnetic Pulse Crimping in Tube-to-Rod Configuration

Ramesh Kumar,Sachin D. Kore 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.8

Magnetic pulse crimping is a solid state, high-speed impact crimping technique. In this paper, copper tube was successfully crimped on the steel 1020 rod. Three types of profiles threaded, knurled, and plain profile were created on the steel rod and then a copper tube was crimped on the rod. The influence of surface profiles on the joint strength, surface roughness and microstructure of the joint were analyzed and compared. Compression-shear tests as well as pull-out tests were carried out to compare the strength of the crimped joint. The result of the pull-out tests as well as compression-shear tests revealed that threaded surface profile on the steel rod gives better strength in comparison to the other two profiles. Along the circumference of the Cu-steel composite rod the microstructure images of the joints were taken and analyzed, it was found that there was no gap along the circumference of the sample crimped at 5.3 kJ of discharge energy with plain profile. For surface roughness, the Ra values of the crimped samples at 5.3 kJ were analyzed and it was found that average Ra value of the sample crimped on the threaded base was highest (0.80 μm) among threaded, knurled, and plain base samples.

Electromagnetic forming and perforation of Al tubes

Sagar Pawar,Sachin D. Kore 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.12

Electromagnetic forming (EMF) is a high energy rate forming process which utilizes electromagnetic force to deform metal workpiece. In this research work, experiments have been conducted to establish the feasibility of electromagnetic forming and perforation (EMFP) of Al tubes. EMFP combines electromagnetic forming with electromagnetic perforation. For the feasibility study split die, pointed and concave punches were designed. The detailed study of the effect of process parameters on EMFP of Al tubes has been carried out. The optimum discharge energy was determined with experimental trials which lead to successful forming and perforation of the tube. In the case of 12-hole perforation with 5 mm stand-off distance, optimum discharge energy observed for pointed punch was 6.2 kJ whereas for the concave punch it reduced to 5.7 kJ. In the case of 36-hole perforation by a concave punch with 10 mm stand-off distance, optimum discharge energy observed was 6.2 kJ. Experimental results show that the concave punches were more suitable for perforation operation as complete removal of blank took place. EMFP overcomes the disadvantages of the formation of burrs and slivers in conventional shearing and perforation.

Numerical Study and Experimental Investigation on Electromagnetic Crimping for Tube-to-Rod Configuration

Getu Tilahun Areda,Sachin D. Kore 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.2

Using low-density material like aluminum to reduce the weight of airframe structure becomes prominent and requires effective joining technology. Electromagnetic crimping is a high-speed joining method that deforms electrically conductive material by discharging high-voltage from the capacitor bank at room temperature. In this study, the effect of discharge energy on joint quality and process parameters is investigated numerically and experimentally. Finite element simulation and analysis were carried out using LS-DYNA™ software by its electromagnetic module. Effects of energies on the effective plastic strain, resultant velocity, displacement, Lorentz force, current densities, magnetic field densities, and maximum shear stress were predicted numerically to determine best energy levels. Based on the result obtained from numerical simulations, three levels of energy were chosen to conduct the experiment. Pull-out strength of the crimped sample was found 95% compared to the strength of the tube. A tube thickness reduction at groove edge, radial displacement of the tube, and groove filling obtained numerically were compared with experiment and found to be in a good agreement. The developed model can be used as a preliminary study to investigate the effect of groove and process parameter on joint quality.

Non-coupled Finite Element Modelling of Electromagnetic Radial Compaction of Pure Aluminium Powder

Nadimetla Thirupathi,Ramesh Kumar,Sachin D. Kore 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.3

In this article, Finite element modelling is described to simulate aluminium powder’s electromagnetic radial powder compaction process. Electromagnetic powder compaction technique is considered a high strain and high-speed powder forming technique in which solenoid coil with uniformly tapered step field shaper is used as forming tool for powder compaction process. In this process, the packing tube that holds the powder acts as a driving medium for the momentum transfer. During experiments, aluminium powder is kept in an electrically conductive driver tube material (in this study, Al 6063 tube). This process utilizes the Lorentz forces for compacting powder to give the required strength for the powder metallurgy component. This paper mainly develops a non-coupled finite element model to simulate the aluminium powder’s electromagnetic powder compaction process. A versatile software Ansys Maxwell was used to analyze the intensities of the distribution of the electromagnetic fields during the electromagnetic forming process. The current curve obtained in the experiment is used as input loading conditions for analyzing electromagnetic fields. After that, for structural analysis of the powder compaction process, Ls-Dyna explicit software is used. The Geologic cap model was established in Ls-Dyna Multiphysics software for modelling powder deformation behaviour. The Johnson-Cook strength model was used to describe the packing tube’s deformation. The FEM analysis helped predict the results of the final shape and size of electromagnetic powder compaction. The developed simulation model has been validated with a series of experiments resulting from the compaction of aluminium powder.

Application of electromagnetic forming in terminal crimping using different types of field shapers

Ashish K. Rajak,Sachin D. Kore 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.9

Mechanical crimping is the most used method of pressure connection for permanent electrical contact in electrical and electronic equipment. Terminal plastic deformation on multi-wire strands is carried out to achieve mechanical strength and electrical conductivity. Electromagnetic (EM) is assumed to be an alternative method to overcome the challenges of spring back in the terminal on tool relaxation, cracks, non-uniform deformation, reduced strength, decreased the durability of joints in conventional crimping tool. Implementation of the field shaper (FS) has been proposed to enhance the magnetic field to concentrate the magnetic pressure at the required location for the effective terminal crimping over the wire strands. In this work, crimping was carried out using FS as a tool. Experiments were carried out utilizing tapered FS, single step FS and double step FS on aluminum terminal over seven strands aluminum wire strands that are commercially utilized for making interconnections. Results like contact length, contact resistance, terminal deformation, surface hardness, cross-section hardness and pull-out tests were found out and compared simultaneously. Also, the test results were compared with the samples crimped using a conventional crimping tool. From the results single step FS was found to be the most efficient FS than double step FS whereas the tapered FS was the least efficient. The results will be helpful in determining the geometry for the field shapers in similar applications.

Designing of field shaper for the electro-magnetic crimping process

Ashish K Rajak,Ramesh Kumar,Sachin D Kore 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.11

Design of a field shaper plays an essential role in the electromagnetic crimping process. It needs to be designed in such a manner that maximum magnetic field is concentrated at the active working zone. Simultaneously it is essential to take care of the mechanical strength of the field shaper so that the von Mises stress acting over the field shaper should always be lower than the strength of the material used for making field shaper. In this manuscript, numerical and experimental work is carried out in the variation of the effective height of the field shaper, to get the most suitable effective working zone height for maximum magnetic pressure acting over the workpiece. Research is carried out over the electrical interconnectors as an application, to achieve maximum crimping of the terminal over the wire strands. Results like the current density, Von-Mises stress, magnetic field, Lorentz force, terminal deformation, and contact length are discussed in detail. These results will help to design a field shaper for different industrial applications.

Numerical and Experimental Study on Effect of Different Types of Field-Shaper on Electromagnetic Terminal-Wire Crimping Process

Ashish K. Rajak,Ramesh Kumar,Hirak Basumatary,Sachin D. Kore 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.3

Electromagnetic terminal-wire crimping (EMTWC) is a type of mechanical joining process. In EMTWC, the terminal is deformed over the wire strands plastically to enhance the mechanical strength by increasing the contact area. A well-crimped electrical interconnection helps to avoid harmful configurations by reducing sparks, overheating, power losses etc. Subsequently, the challenge to minimize various disadvantages of conventional mechanical terminal-wire crimping process like non-uniform deformation, decreased durability, cracks, etc., can be overcome by the electromagnetic crimping process. In this work, application of the fieldshaper has been proposed to concentrate the magnetic pressure at the desired location for effective wire crimping. Numerical analysis was carried out using LS-DYNATM on three different types of field-shaper namely single-step, double-step and tapered. In all the three field-shaper, the total length, the outer diameter and the effective working length were constant. The samples used was an aluminum terminal and seven strands of aluminum wires which are commercially used for making electrical inter connections. Experiments were carried out based on the results obtained through numerical analysis. Experimental and numerical results were in agreement and the error was less than 10%. The efficiency of single-step field-shaper was found to be better compared to double-step and tapered fieldshaper.

FSW of low carbon steel using tungsten carbide (WC-10wt.%Co) based tool material

Avinish Tiwari,Piyush Singh,Pardeep Pankaj,Pankaj Biswas,Sachin D Kore 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.10

Low carbon steels could be simply welded by conventional fusion welding processes. However, fusion joining of these steels results to the problems related to melting of metal and solidification of weld pool. In the present study, friction stir welding (FSW) of low carbon steel plates was undertaken using tungsten alloy tool to determine the effects of welding parameters on joint quality. Welded joints were characterized by microstructural and mechanical properties. Onion rings, banded structure and swirl zone were observed as a result of process temperature, strain rate, plastic deformation, and material transportation. The results indicate that the grain size of the weld zone is different from the base metal (BM) and slightly lesser to the base metal in the middle region of stir zone. Comparing the advancing side (AS) and retreating side, grain size was similar in the heat affected zone and different in the thermo-mechanically affected zone. The microstructure provides the suitable relationship for the properties and micro hardness of the welded region. Tungsten carbides rich areas were found in the stir zone performed at high heat input weld condition. Interestingly, there is noticeable change in grain size and grain distribution of the tungsten tool after welding.