Analysis of short circuit transfer behavior using acoustic signal detection

The stability of a short circuiting period is important to obtain the desired weld quality. The objective of this research is to analyze the uniformity of liquid bridge disruption period during short circuit mode affected by various shielding gas compositions. The shielding gas compositions of 100% CO2 and 84%Ar+2%O2+14%CO2 were used in this study. Short circuiting period was detected by using acoustic signals emitting from the arc. Acoustic data were recorded by using multimedia function of XP windows audio card through a high sensitivity microphone. The results of short circuit acoustic data were analyzed by using continuous wavelet transformation for classifying the difference of acoustic emitting mechanism of electrode tip touching with base metal and pinching cut-off. For 84%Ar+2%O2+14%CO2 shielding gas, it clearly showed smoothershort circuit transfer than that of CO2 shielding gas. CO2 shielding gas gave large variation in disruption period comparing with that of 84%Ar+2%O2+14%CO2 gas mixture

ホットワイヤ・レーザ溶接法による厚鋼板立向き溶接技術の開発

広島大学(Hiroshima University)博士(工学)Doctor of Engineering in Mechanical Science and Engineeringdoctora

Digitalized Evaluation of Welder Skill by using Cyclogram Characteristics

This paper proposes a new evaluation method for welder skill in Gas Metal Arc Welding (GMAW) process in term of studying the natural hand-movement that affect the signal processing. Weld quality of GMAW generally depends on welder skill to maintain the uniform of hand movement. Therefore, the welder skill is considered as the critical point to maintain the weld quality. Hence, welding current and voltage signal could be an alternative way for monitoring and assessing the skill of welder based on the signal variation of the welding process. This research defines in two stages, first is the physical-simulation using robot welding Fanuc Arc Mate 100iB and monitoring the signal using Cyclogram technique. Second is comparing the Cyclogram characteristic of robot welding and manual welder. By using the data acquired, the characteristic of Cyclogram was analyzed by varying Torch angle change (W1) and Torch-height change (W2) to investigate the signal processing. Furthermore, the data of current and voltage were generated as a quantitative method to determine the size of Cyclogram. The results show that the method capable of differentiating the two beginner welders compare to the robot welding performance based area of Cyclogram characteristic. Finally, the Cyclogram could be a novel tool for monitoring and evaluating the welder skill with high sensitivity to detect hand motion

Effect of Double Pulse MIG Welding on Porosity Formation on Aluminium 5083 Fillet Joint

In this article, parameters of Double-Pulse Metal Inert Gas Welding (DP-MIG) was used for minimising a porosity formation in a T-joint fillet weld. AA5083-H112 aluminium alloy (Non-heat treatable series) with the plate thickness of 10 millimetres is base metal for this study. Welding consumables were filler wire ER5356 with a diameter of 1.2 millimetres and shielded by industrial argon gas. Three majorities parameter of DP-MIG were Delta wire feed (m/min), Frequency (Hz) and Duty cycle (%). Measurable signal current pattern and opened porosity on the fractured surface were couple observed to study their relationships. An appropriate image processing technique was employed to quantitative measuring and calculating a size grouping area of several opened porosities overall weld length, precisely. The result found that the optimal was used a low-level of Delta wire feed of 0.8 m/min, a high-level of a frequency of 5.0 Hz, a mid-level of the duty cycle 30 % and a high travel speed 60 cm/min could minimise the porosity formation with complete penetration

Estimation of Contact Tip to Work Distance (CTWD) using Artificial Neural Network (ANN) in GMAW

A method for optimizing monitoring by using Artificial Neural Network (ANN) technique was proposed based on instability of arc voltage signal and welding current signal of solid wire electrode (GMAW). This technique is not only for effective process modeling, but also to illustrate the correlation between the input and output parameters responses. The algorithms of monitoring were developed in time domain by carrying out the Moving Average (M.A) and Root Mean Square (RMS) based on the welding experiment parameters such as travel speed, thickness of specimen, feeding speed, and wire electrode diameter to detect and estimate with a satisfactory sample size. Experiment data was divided into three subsets: train (70%), validation (15%), and test (15%). Error back-propagation of Levenberg-Marquardt algorithm was used to train for this algorithm. The proposed algorithms on this paper were used to estimate the variety the Contact Tip to Work Distance (CTWD) through Mean Square Error (MSE). Based on the results, the algorithms have shown that be able to detect changes in CTWD automatically and real time with takes 0.147 seconds (MSE 0.0087)

Single-Pass Cladding Process Using Hot-wire Gas Metal Arc Welding Technique

The aim of this study is to improve cladding process productivity by high production rate with low dilution process by specifying technique as hot-wire GMAW process. The base metal of carbon steel A516 Gr70 was cladded by austenitic stainless steel 309LSi for creating a buttering layer and stainless steel 308LSi for hot-wire filler for topping a cladding layer in a one-pass run. The studied parameters this experiment consist of the feeding ratio of hot wire feeding speed per GMAW wire feeding speed and travel speed. Welding phenomenon during welding was observed by CCD camera with specifying the optical device to see the appropriate condition. The result showed the hot-wire GMAW cladding process could reduce cycle time 3.5 times compare with conventional FCAW cladding process. Moreover, dilution of this process could decrease lower than 15% with acceptable FN 3 on the top of weld surface. Therefore, single pass cladding process achieved by using this method with low dilution by still keep microstructure capability

Selection of Welding Process for Repairing Shredder Hammer by Integrated Data Envelopment Analysis (DEA) and P-robust Technique

The Selection of the welding process is one of the most significant decision-making problems, and it involves a wide range of information following the type of product. Hence, the automation of knowledge through a knowledge-based system will significantly enhance the decision-making process and simplify for identifying the most appropriate welding processes. The aims of this paper for explicates a knowledge-based system developed for recognising the most suitable welding processes for repairing shredder hammer by using data envelopment analysis (DEA) and p-robust technique. The proposed approach is used for ranking six welding processes which are commonly used, namely shielded metal arc welding (SMAW), flux cored arc welding (FCAW), submerged arc welding (SAW), oxyacetylene gas welding (OAW), gas tungsten arc welding (GTAW), and gas metal arc welding (GMAW). In order to determine the best welding process among competitive welding processes for repairing of shredder hammer, ten parameters are used, namely the availability of consumable, welding process type (manual and automatic), flexibility of welding position, weld-ability on base metal, initial preparation required, welding procedures, post-weld cleaning, capital cost, operating factor, and deposition rate. Furthermore, the sensitivity analysis of regret value (p) is investigated in three cases proposed

Laser Welding on Cerclage Wire Joining in Femur Surgery

Stainless steel wires with fiber-laser welding on lap joints are first proposed in this study to be used as cerclage wire joints for modern femur surgery, because of their potentially larger joint strength and less loosening failure than traditional joint devices. In this feasibility study, an experiment was set up to determine adequate parameters for the laser welding process in order to ensure that the wire joint of cerclage has good weld appearance, free oxidation, and suitable joint strength. A stainless steel wire 316L with a diameter of 1.6 mm, flare-welded on lap joint was used in the experiment as a specimen cerclage wire joint. Two major effective parameters were chosen for controlling a suitable fusion weld, including charge voltage and multiple frequencies of the laser irradiation. The adequate area of the laser parameters was determined from the experiment, including the ranges of charge voltage, multiple frequencies, and pulse width. The suitable welded lengths of specimens were also studied in the mechanical test to validate the joint strength. Suggested welded length has a better tensile strength than traditional cerclage joints. The paper concludes that the stainless wire joints with a fiber laser weld represents a promising alternative to traditional cerclage joint devices for modern femur surgery

Effect of Double Pulse MIG Welding on Porosity Formation on Aluminium 5083 Fillet Joint

In this article, parameters of Double-Pulse Metal Inert Gas Welding (DP-MIG) was used for minimising a porosity formation in a T-joint fillet weld. AA5083-H112 aluminium alloy (Non-heat treatable series) with the plate thickness of 10 millimetres is base metal for this study. Welding consumables were filler wire ER5356 with a diameter of 1.2 millimetres and shielded by industrial argon gas. Three majorities parameter of DP-MIG were Delta wire feed (m/min), Frequency (Hz) and Duty cycle (%). Measurable signal current pattern and opened porosity on the fractured surface were couple observed to study their relationships. An appropriate image processing technique was employed to quantitative measuring and calculating a size grouping area of several opened porosities overall weld length, precisely. The result found that the optimal was used a low-level of Delta wire feed of 0.8 m/min, a high-level of a frequency of 5.0 Hz, a mid-level of the duty cycle 30 % and a high travel speed 60 cm/min could minimise the porosity formation with complete penetration