Showing papers on "Electric resistance welding published in 2019"

Resistance welding of thermoplastic composites with a nanocomposite heating element

Abstract: In this study, we propose a new heating element (HE) for the resistance welding of thermoplastic composites. This HE is made of polyetherimide (PEI), rendered electrically conductive by the addition of 10% wt. multi-wall carbon nanotubes (MWCNT) (conductivity of 0.79 S cm-1). The new HE was successfully used to weld carbon fibre/poly (ether ketone) (CF/PEEK) laminates in a single lap shear configuration, leading to a lap shear strength of up to 19.6 MPa. Observations of the fracture surfaces revealed a cohesive failure mode within the nanocomposite HE and non-uniform heating over the weld area. It is believed that PEI/MWCNT HE present an interesting alternative to current HE, although more work is needed to improve the temperature homogeneity over the weld area.

Structural evaluation and mechanical properties of AZ31/SiC nano-composite produced by friction stir welding process at various welding speeds:

Abstract: A metal matrix composite made of AZ31 containing SiC nano-particles was successfully produced by friction stir welding (FSW), and the effect of processing parameters such as rotational and transver...

Formation of multi-axial welding stresses due to material behaviour during fabrication of high-strength steel components

Abstract: Today, an expanding application of high-strength steels in modern welded constructions can be observed. The economical use of these steel grades largely depends on the strength and reliability of the weldments. Therefore, the special microstructure and mechanical properties of these grades have to be taken into account by keener working ranges regarding the welding parameters. However, performance and safety of welded components are strongly affected by the stresses occurring during and after welding fabrication locally in the weld seam and globally in the whole component, especially if the shrinkage and distortion due to welding are restrained. Some extensive studies describe the optimization of the welding stresses and the metallurgical effects regarding an adapted welding heat control. Lower working temperatures revealed to be particularly effective to reduce the local and global welding-induced residual stresses of the complete weld significantly. However, decreased interpass temperatures cause concurrently higher stresses during welding fabrication. This work shows strategies to reduce these in-process stresses. With help of multi-axial welding stress analyses in component-related weld tests, using a special 2-MN-testing facility, differences in stress build-up are described in detail for root welds, filler layers and subsequent cooling to ambient temperature.

Microstructure and Fracture Behavior of Refill Friction Stir Spot Welded Joints of AA2024 Using a Novel Refill Technique

Abstract: Keyhole at the end of a conventional friction stir welded (FSW) joint is one of the major concerns in certain applications. To address this issue, a novel keyhole refilling technique was developed for conventional friction stir spot welding (FSSW) using resistance spot welding (RSW). A three-phase secondary rectifier resistance welder was adapted for the refill of the keyhole in the 1.5 mm + 1.5 mm friction stir spot welded 2024-T4 aluminum alloy joint. The microstructure and tensile shear fracture behavior were compared for both the unfilled and refilled specimens. The results show that the plug and keyhole are dominated by solid state welding with some localized zones by fusion welding. The refill process significantly improved the maximum load capacity in tensile shear testing as the corona ring is enlarged leading to a larger bonding area. Moreover, the tensile shear fracture occurs in the refilled FSSW specimens at the corona bonding zone, while the fracture occurs at the hook zone in the unfilled keyhole.

Weldability of a zirconium alloy comparing resistance and pulsed laser methods

Abstract: The current study intends to characterize the microstructure resulting from the autogenous welding of zircaloy-4 and its influence on the mechanical behavior. For comparison purposes, laser beam welding (LBW) and electric resistance welding (ERW) were used for joint tubes to sleeves suitable for fuel elements of the Brazilian power reactor Angra 1. The tubes measured 14.15 mm external diameter with a wall thickness of 1.76 mm and the sleeves measured 15.61 internal diameter with a wall thickness of 0.64 mm. Under conventional ERW, the process parameters were chosen to produce an approximately 2 mm wide weld bead appropriate for the thermo-mechanical loading of the component. However, laser methods could be an alternative for automation and reproductiity. The microstructure in the fusion zone (FZ) for the welding processes was characterized by α martensite for LBW and α Widmanstatten for ERW. It was verified tin segregation in specific regions of the ERW coupons, however, without affecting the tensile strength or the hardness of the coupons. The maximum load for ERW coupons were about 8 kN, higher than LBW case (3 kN), although both above the standard requirements. The relative low value of LBW tensile strength was due to the gap between the tube and the sleeve, as conceived for ERW, and not optimized for the laser process. Loss of coolant accident (LOCA) shown a white ZrO2 coating on the LBW surface as a result of massive oxidation of the resolidified material.

Experimental Study of the Residual Stresses in Girth Weld of Natural Gas Transmission Pipeline

Abstract: In order to achieve integrated condition in the girth welding of high pressure natural gas transmission pipelines, the weld zones and its surrounding area should have good mechanical properties. Residual stresses are an important defect especially in the girth welding of the pipeline. In this study, two API X70 steel pipes (with spiral seam weld) of 56 inches outside diameter and 0.780 inch wall thickness were girth welded first. The hole drilling tests were conducted for residual stress measurement on the surfaces of the pipes. The hoop tensile residual stress on the external surface of the pipe with the maximum value equal to 318-MPa was measured on the weld centerline. Hoop residual stress distributions in the internal and external surfaces of the pipe were approximately similar. The maximum axial residual stress was observed in the heat affected zone (a distance of approximately 30 mm from the weld centerline). The maximum axial residual stress on the external surface of the pipe was tensile, equal to 137 MPa, and on the internal surface of the pipe was compressive, equal to 135-MPa. Axial residual stress magnitudes in the weld centerline on the internal and external surfaces of the pipe were close together. Away from the weld centerline, axial residual stresses on the internal and external surfaces showed the opposite behavior. Therefore, in the girth welding of natural gas transmission pipelines, the peripheral direction on the internal surface of the pipe is the critical zone and have the highest tensile residual stresses.

Multi-scale polybasic high-pressure and high-conductivity copper-chromium-zirconium alloy material and preparation method thereof

Abstract: The invention discloses a multi-scale polybasic high-pressure and high-conductivity copper-chromium-zirconium alloy material and a preparation method thereof and belongs to the field of nonferrous metal processing. The alloy material is composed of, by weight, Cr: 0.05-0.75%, Zr: 0.05-0.2% and the balance Cu. The alloy material is obtained by the process of mixing, feeding, smelting, casting, homogenizing annealing treatment, hot extrusion, solid solution treatment, cold drawing, timing treatment, secondary cold drawing and online annealing treatment. Tensile-resistant strength of the alloy material is 300-700 MPa, the yield strength is 150-600 MPa, the elongation rate is 10-30%, the conducting rate is 70-95% IACS, the softening temperature is 500-600 DEG C, and the repeated bending frequency is 1*10 -1*10 . The alloy material can fully meet the demands of precision cables, electrified railway contact wires, resistance welding electrodes and other important areas.

Resistance welded composite joints strengthened by carbon fiber felt: mechanical properties, failure modes and mechanism

Abstract: The joining of composite parts with weight reduction and cost saving is being developed to improve aircraft performance. The high-efficiency resistance welding technology was hence explored for joining glass fabric reinforced polyetherimide (GF/PEI) laminates in this work and a composite PEI films reinforced with carbon fiber felt (CFF) reinforced laminae was embedded into the interface of the welding region to enhanced the strength of the joints of GF/PEI. The effects of CFF incorporation on the welding speed and the lap shear strength (LSS) of welded joints were investigated in comparison with those of the CFF-uncontained welded joints. The CFF-incorporated resistance welding speed was accelerated and its LSS was enhanced evidently, the maximum LSS value reached 32 MPa. The fracture mode and mechanism of welding implants, which varied with t w from the linear tearing to the annular tearing due to the coupling effect of the improvement of PEI molten state and the occurrence of PEI thermal degradation, were illuminated according to the test results from ultrasonic C-scan and SEM.

Heat development of the contact area during capacitor discharge welding

Abstract: Capacitor discharge welding primarily applies to projection welding. Components with ring projections up to 200 mm diameter can be welded with peak currents up to 1000 kA and welding times less than 10 ms. Weld nuggets are expected to occur, as the CD-Welding belongs to resistance welding. Although the required strength is given, welding nuggets in cross-sections cannot invariably be verified. According to recent researches, joining occurs without a welding nugget, but with metal vaporisation and linked activation of the surfaces. This process is called short-time welding with high thermal current density. The type of the welded joint depends on the heating properties in the weld zone. Different welding energies, electrode forces and welding times result in different welded joints. The process-specific advantages can be taken, and new application areas for CD welding can be developed by knowing the cause-and-effect relationships.

Resistance Welding in Smart Textile

Abstract: With the growing Smart Textile industry, there is currently increasing interest in mapping the possibilities and quality of contacting embroidered conductive patterns. This paper deals with one of the contacting options currently in use, the method of resistance welding. Furthermore, the paper deals with the testing of these realized samples. All created specimens went through a dry heat test, thermal cycling test and washing test. Tests were designed to determine the resistivity of each pattern against both thermal and mechanical stresses.

Characteristics of resistance projection–welded aluminum-copper interconnects

Abstract: This paper describes the use of resistance projection welding of lap joints between tinned copper terminals with flat aluminum conductors. With the exception of resistance brazing, resistance welding, which has been established for many decades, is currently not used for joining dissimilar metal joints made of copper and aluminum. The use of this technology could potentially result in particularly cost-effective joints that are easily scalable to different sizes of terminals. For the necessary current density during the welding process, a mechanically embossed welding projection in the copper conductor surface is required. During the welding process, the projection moves into the softer aluminum material without being deformed. The projection expresses part of the brittle liquid intermetallic compounds produced. Shear tensile tests, electrical conductivity measurements and micrographs are used to assess the technical properties of the joint. The presented results show that the created intermetallic joint has good electrical and mechanical properties despite pronounced intermetallic AlCu layers.

Power Supply of Resistance Welding Machine with Reactive Power Compensation

Abstract: An approach to application of power supplies for resistance welding machines based on three-to-one matrix converter as reactive power compensator is offered. By setting a predetermined phase shift of the input current, it is possible to achieve reactive power compensation also for the consumer demand. The range of variation of the possible compensation angles is limited by the electromagnetic compatibility standards for the boundary current harmonic levels. Proposed control system is simulated using MATLAB. The simulation results confirmed high effectiveness of proposed approach.

Subjective Factors Consideration in the Selection of Welding Technique for Welded Tube Manufacturing

Abstract: In choosing the right welding process for an application like welded tube manufacturing, the manufacturing engineers have to take into account a large number of selection criteria. Choosing the right welding process for any application is difficult not only due to multiple factors affecting the decision but also due to a number of emerging new welding techniques becoming available as alternatives. Some of the alternative welding processes for manufacturing tubes have been Fretz-Moon process (FM), low-frequency (LF) as well as high-frequency (HF) alternating current resistance welding, direct current (DC)-based resistance welding in addition to gas metal arc welding (GMAW), and submerged arc welding (SAW) in some specific applications. A systematic examination of the decision situation may lead us to an appropriate choice rather than basing the decision on one factor or the other in stand-alone manner. This paper presents an analytic hierarchy process (AHP)- based decision analysis for the selection of welding process in a case of manufacturing small diameter steel tubes.

Hybrid Energy Storage System of Power Supply for Micro Resistance Welding

Abstract: This paper proposes a high-efficiency energy storage system within the micro resistance welding device based on battery-supercapacitor semi-active hybrid topology. A SEPIC converter is considered for power distribution between energy storages in order to improve the Li-ion battery performance in terms of cycle life and to increase the efficiency of the overall energy storage system. A comprehensive analysis of energy storage system losses has shown that the efficiency of the proposed topology is 92% at the target switching frequency of 100 kHz. Finally, the theoretical analysis is validated by simulation results, which illustrate the supercapacitor charging process and voltage and current traces of the SEPIC converter individual components.

Investigation of a dissimilar vitreloy 105 to grade 2 titanium laser weld

Abstract: The unique combination of mechanical properties and the ability to be processed using injection molding techniques makes bulk metallic glasses (BMGs) excellent candidates for use in engnineering applications, especially in the medical device industry. Widespread use of BMGs is hindered by their inability to be joined to common engineering materials (ex. titanium) with standard fusion welding techniques (ex. laser welding). In this paper a definitive screening design experiment was performed to optimize a dissimilar Vitreloy 105 to grade 2 titanium laser weld. The optimized weld was then characterized using nanoindentation, scanning electron micrscopy, micro cantilever beam bending, and transmission electron microscopy. It was found that the optimized weld had lower hardness, a more uniform structure, and better performance than the baseline seam weld between the dissimilar materials. The microstructural and micromechanical characterization of the optimized joints showed variation in local mechanical properties that were correlated to chemistry and microstructure ranging from brittle fracture at low loads to ductility and toughness arising from shear band blunting. Not only did the optimized welding process confrim that Vitreloy 105 could be successfully laser joined to grade 2 titanium with properties acceptable for many applications, the investigation into the local structure and properties of the joint revealed the possibility of creating ductile metallic glass composites by controlling the chemistry and structure of the intermetalic zone while processing.

Button cell and manufacturing method thereof

Abstract: The invention provides a button cell and a manufacturing method thereof. The button cell comprises a package assembly and a battery roll core. In the actual application process, a battery cup and a battery cover play a protection role; a seal rubber ring plays a sealing and waterproofing function; besides, when a tab needs to be welded, the tab is positioned, and electric resistance welding operation is carried out on the battery cup and/ or the battery cover, so that the electric resistance welding is carried out on the contact portion between the tab in the center position of the battery roll core and the battery cup and/ or the battery cover to form a center welding layer, and the electric resistance welding is carried out on the contact portion between the tab at the edge position of the battery roll core and the battery cup and/ or the battery cover to form an edge welding layer; the center welding layer and the edge welding layer can prevent the phenomenon of "explosion welding"occurred in the tabs, thereby greatly improving welding stability of the tabs; and compared with a conventional laser welding mode, the provided welding mode is higher in welding safety factor, and there is no risk that the laser directly breaks down the battery cup or the battery cover.

Investigation of RSW process on three-layer joining of steel to 6061-T8 aluminum

Abstract: In this article, the RSW process (Resistance Spot Welding) on 6061-T8 aluminum alloy was studied. Spot resistance welding of two-layer plates is difficult and has very low mechanical proper...

Feedforward type electric resistance welding quality monitoring system and method

Abstract: The invention discloses a feedforward type electric resistance welding quality monitoring system and method. The system includes a server and a sensor group fixedly arranged in a working area and non-working area of an electric resistance welding gun, the sensor group is in signal connection with the server, and the sensor group includes an analog quantity sensing signal detection window, an A/D signal acquisition processing circuit, a visual signal detection window and lower computer. The method comprises the following steps that (1) the electric resistance welding gun to be detected is controlled to be periodically in the sensing signal detection window and the visual signal detection window; (2) analog quantity signals detected by the analog sensing signal detection window are collected; (3) end face pictures of upper and lower electrode caps are collected; and (4), whether the analog quantity signals are within a normal range is judged, and whether the upper and lower electrode caps are centered and the grinding states of the electrode caps are judged according to the upper and lower electrode cap pictures. Early warning can be carried out, maintenance and repair are pulled, and therefore generation and overflow of defective solder joints are reduced or even avoided.

Welding and joining of shape memory alloys

Abstract: Shape memory alloys are difficult to weld due to their own special properties, which lead to the problems of joints such as low strength, formation of intermetallic compounds, variations in phase transformation effects and its temperature, and changes of shape memory effect. However, different welding and joining processes are attempted to solve these problems. In this chapter, various welding processes such as tungsten inert gas welding, plasma welding, laser beam welding, electron beam welding, resistance welding, friction stir welding, friction welding, explosive welding, ultrasonic welding, diffusion bonding, adhesive bonding, brazing, and soldering are discussed on process capabilities and challenges to obtain shape memory welds.

Operation monitoring device, method and program for high-frequency resistance welding and induction heated welding of electric resistance welded steel pipe

Abstract: The objective of the present invention is to enable accurate detection of a mismatch during electric resistance welding. This operation monitoring device for high-frequency resistance welding and induction heated welding of an electric resistance welded steel pipe, in which a strip-shaped metal sheet is continuously formed into a cylindrical shape by means of a group of rollers while being conveyed from an upstream side to a downstream side, and in which the two edge portions, in the circumferential direction, of the metal sheet, which are caused to converge into a V-shape, are caused to melt by the application of heat and are caused to abut one another, is characterized by being provided with a means for detecting a mismatch by recognizing a non-uniformity between light-emitting regions of a metal part, on both sides, in the circumferential direction, of the abutting position on an outer surface or an inner surface of the metal plate, on the basis of an image of a region including a V-convergence location, which is a location at which the two edge portions in the circumferential direction converge into said V-shape, and said metal part which is caused to flow out onto the surface of the metal plate by means of an electromagnetic force downstream of the V-convergence location, wherein said image is captured by means of an image capturing device from an outer surface side or an inner surface side of the metal plate that has been formed into said cylindrical shape.

Application of Resistance Welding Machines for Production of Precision Aluminium Joints

Abstract: Electric resistance butt welding of aluminium alloys through thin metal interlayers has been investigated. The effectiveness of using not high capacity resistance welding machines for getting of precision joints has been shown. The technology of resistance butt welding of aluminium alloy 6063 through thin multilayer intermediate layers of aluminium 1050 foil has been developed. The results of microstructure and mechanical strength analysis have been shown.

Stability Analysis of Battery-Supercapacitor Energy Storage System for Resistance Welding

Abstract: This paper proposes a high-efficiency energy storage system within the micro resistance welding device based on battery-supercapacitor semi-active hybrid topology. A SEPIC converter is chosen for energy management between individual energy storages because it can considerably improve Li-ion battery performance in terms of shelf life and increase the overall system efficiency compared to other topologies. Accurate state-space mathematical model of SEPIC converter used within the hybrid energy storage system is obtained by means of average values analysis. It is then used to analyze the overall hybrid energy storage system stability by means of Nyquist stability criterion. The results show that the proposed battery-supercapacitor hybrid energy storage system should be characterized by stable behavior regardless of the variations of duty cycle and load current over a wide range of regimes.

Automobile member having resistance weld

Abstract: Provided is an automotive member, or particularly, a steel sheet having a tensile strength exceeding 900 MPa. The automotive member has a resistance weld for fixing two or more steel sheets containing a predetermined composition, in which a maximum hardness (HVBM) in a heat-affected zone of the resistance weld is at least 1.1 times hardness (HVW) of a nugget in the resistance weld formed in a softest steel sheet of a sheet set during resistance welding, and furthermore, an average grain size of a steel sheet structure of the heat-affected zone within 2 mm in a direction at a right angle to a sheet thickness from an end part of the nugget of the high-strength steel sheet is 3 μm or less, and a minimum hardness (HVmin) in the heat-affected zone is at least 90% of hardness (HVα) of the high-strength steel sheet before the resistance welding.

Alignment detection device and method for resistance welding gun

Abstract: The invention discloses an alignment detection device and method for a resistance welding gun. The device comprises an annular light source, a lower computer, an upper computer and an upper camera anda lower camera which are symmetrically fixed about the horizontal plane. The method comprises the following steps that (1), electrode caps of a to-be-detected resistance welding gun are adjusted to be in an inspected state; (2), images of end faces of the upper electrode cap and the lower electrode cap of the to-be-detected resistance welding gun are acquired; (3), central point coordinates of the upper electrode cap and the lower electrode cap in the images of the end faces of the upper electrode cap and the lower electrode cap are determined by adopting an image processing method; (4), thecentral point coordinates of the upper electrode cap and the lower electrode cap are compared with standard central point coordinates of the upper electrode cap and the lower electrode cap, and whether the alignment of the upper electrode cap and the lower electrode cap is within a preset threshold value range or not is judged; and (5), the alignment state of the upper electrode cap and the lowerelectrode cap is judged according to the preset threshold value range. According to the alignment detection device and method for the resistance welding gun, alignment detection of the feedforward type resistance welding gun electrode caps can be achieved, therefore, timely early warning is achieved, maintaining and repairing are promoted, and generating and overflowing of welding defects are reduced and even avoided.