Assessment of feedback variables for through the arc seam tracking in robotic gas metal arc welding

Author(s):  
Jianming Tao ◽  
P. Levick
2018 ◽  
Vol 15 (6) ◽  
pp. 172988141881620
Author(s):  
Reza Ebrahimpour ◽  
Rasul Fesharakifard ◽  
Seyed Mehdi Rezaei

Welding is one of the most common method of connecting parts. Welding methods and processes are very diverse. Welding can be of fusion or solid state types. Arc welding, which is classified as fusion method, is the most widespread method of welding, and it involves many processes. In gas metal arc welding or metal inert gas–metal active gas, the protection of the molten weld pool is carried out by a shielding gas and the filler metal is in the form of wire which is automatically fed to the molten weld pool. As a semi-metallic arc process, the gas metal arc welding is a very good process for robotic welding. In this article, to conduct the metal active gas welding torch, an auxiliary ball screw servomechanism is proposed to move under a welder robot to track the welded seam. This servomechanism acts as a moving fixture and operates separately from the robot. At last, a decentralized control method based on adaptive sliding mode is designed and implemented on the fixture to provide the desired motion. Experimental results demonstrate an appropriate accuracy of seam tracking and error compensation by the proposed method.


1998 ◽  
Vol 120 (3) ◽  
pp. 600-608 ◽  
Author(s):  
S. B. Zhang ◽  
Y. M. Zhang ◽  
R. Kovacevic

A novel seam tracking technology based on high frequency ultrasound is developed in order to achieve high accuracy in weld seam identification. The transmission efficiency of the ultrasound is critical for obtaining a sufficient echo amplitude. Since the transmission efficiency is determined by the difference in impedance between the piezoelectric ceramic and air, match layers are designed to optimize the transmission efficiency by matching impedance. Since the air impedance depends on the density and velocity of the ultrasound, which both depend on the temperature, the optimization has been done for a wide bandwidth. Also, the receiving circuit is designed so that its resonance frequency matches the frequency of the ultrasound. As a result, the sensitivity of the noncontact ultrasonic sensor is improved 80-fold. By properly designing the focal length of the transducer, a high resolution ultrasound beam, 0.5 mm in diameter, is achieved. Based on the proposed sensing technology, a noncontact seam tracking system has been developed. Applications of the developed system in gas tungsten arc welding (GTAW) and CO2 gas metal arc welding (GMAW) processes show that a tracking accuracy of 0.5 mm is guaranteed despite the arc light, spatter, high temperature, joint configuration, small gap, etc.


2007 ◽  
Vol 1 (3) ◽  
pp. 268-273 ◽  
Author(s):  
Jinqiang Gao ◽  
Chuansong Wu ◽  
Xizhang Liu ◽  
Dianxiu Xia

Author(s):  
C D Yoo ◽  
H-K Sunwoo ◽  
K-I Koh

The arc sensor has been widely used to detect the weld seam by monitoring welding current or voltage variation during weaving in gas metal arc welding (GMAW). In this work, the arc light intensity and welding resistance are utilized as the seam tracking sensor. Signal characteristics of the arc light intensity and welding resistance are compared when argon and CO2 gas are used for shielding. The performance of signal processing methods such as the least squares and integration methods is evaluated experimentally. It is found that the arc light intensity provides higher quality signals than welding resistance with CO2 gas. While both signal processing methods demonstrate almost equal seam tracking capabilities, the integration method appears to be more efficient because of the short computation time.


2017 ◽  
Vol 248 ◽  
pp. 18-30 ◽  
Author(s):  
Yanling Xu ◽  
Na Lv ◽  
Gu Fang ◽  
Shaofeng Du ◽  
Wenjun Zhao ◽  
...  

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