Dissertation > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding general issues > Welding automation technology

The Automatic Welding System of Gas Bottle and Bottom Ring Based on Machine Vision

Author LuJinYun
Tutor PanHaiPeng
School Zhejiang University of Technology
Course Control Theory and Control Engineering
Keywords Machine vision Automatic welding Welding seam image recognition Cannyoperator Mathematical morphology
Type Master's thesis
Year 2013
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China is a big country to produce and use of gas bottle. The welding of bottle body andbottom ring is the first welding process in the gas bottle production process. At present, thewelding of the gas bottle and bottom ring is mainly manual welding or semi-automaticwelding in China. It has shortcomings of unstable welding quality, low welding efficiency,high labor intensity, poor working environment and human health damage. And in recentyears the manual welding costs is more and more high, enterprises need the correspondingautomation welding machine to enhance competitiveness. According to the current weldingsituation of the gas bottle and bottom ring, the main research of this paper is as follows:(1) According to the physical characteristics of the gas bottle and bottom ring and therequirements of welding process, this paper researches and designs the mechanical system ofautomatic welding machine. It mainly includes the welding gun clamping device, the bottomring gripping and conveying device, the bottle gripping and conveying device, the positiondevice of weldment and rotation device of the spindle. The welding gun clamping device withthree degrees of freedom can make welding gun accurately aim at the central position ofwelding seam. Bottom ring gripping and conveying device adopts the permanent magnetsucker as grasping structure and swing cylinder as actuator, which reduces the cost ofdevelopment. Bottle gripping and conveying device adopts linear guide, ball screw and servomotor as drive assembly, can accurately capture and transmission. Weldment shaft rotatingdevice can control shaft speed by DC motor during the welding and rapidly locate solder jointby the oscillating cylinder.(2) This paper calculates and selects the standard devices in welding machine, includingstandard cylinder, swing cylinder, linear slide, ball screw, servo motor, magnetic powderbrake and vacuum sucker. This paper discusses the selection effects of two different speeds ofthe swing cylinder in bottom ring gripping and conveying device. This paper obtains the lifelength of three different width of linear guide rail in the bottle gripping and conveying device.(3) In order to achieve the automatic identification of the weld seam, this paper studiesthe Roberts edge detection operator, the Sobel edge detection operator, the Prewitt edgedetection operator, the Canny edge detection operator and the mathematical morphology edgedetection operator, and puts forward based on Canny algorithm and mathematical morphology edge detection method to implement the weld edge detection. This papercalculates the curve of the weld center position by local-domain scanning method. The resultsof simulation show that this method can get the clear weld seam edge and center curve.

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