| As a relatively mature material forming technology,welding has been widely used in many fields such as automobiles,aerospace,electromechanical equipment manufacturing and petrochemicals,etc.In order to ensure the use safety of welded products,it is often necessary to perform a certain inspection and evaluation on the appearance quality of the welds after welding.So far,the processes mentioned above have been mainly achieved by professionals with inspection experience through visual inspection or using measuring tools such as weld gauges.These manual methods of detection are not only inefficient,and the detection accuracy of them also largely depends on the quality and ability of the inspectors,which makes it relatively subjective.With the continuous improvement of product welding quality requirements,traditional methods of appearance inspection have been unable to meet the demands of modern welding production,and it has been an inevitable trend for the development of welding industry to realize the automation and intelligent of the inspection and evaluation of the appearance quality of welds.Based on the structural characteristics of butt welds and fillet welds,an inspection and evaluation system based on two-dimensional laser ranging sensors for weld appearance quality was developed in this paper,which can realize non-contact,highprecision,intelligent detection and evaluation of the appearance quality of butt welds and fillet welds in a certain size range.The detection device is formed of industrial computer,servo motor,motor drive module and two-dimensional laser ranging sensor,etc.The detection software mainly includes modules such as motion control,detection control,quantitative geometric calculation and appearance quality evaluation,etc.During the detection process,the two-dimensional laser ranging sensor is driven by the servo motor under the control of the industrial computer to perform a contactless scanning for the surface of the measured weld and obtains the geometric information of the weld surface in the unit of contour line.The inspection system is able to process the contour data of the weld surface through a special algorithm built into it,automatically calculate and extract the geometric parameters such as width,height and angular distortion of the weld,as well as weld surface defects such as undercut,overlap and burn-through,etc.Finally,a quantitative evaluation of the appearance quality of the measured weld was performed in accordance with the relevant welding quality standards.In order to meet the needs of practical engineering applications,the effect to the detection accuracy of factors such as the repeat accuracy of the sensor,the surface state of the measured welds,the inclination of the test pieces during the scanning process,and the settings of algorithm parameters were systematically studied in this paper,as well as the related solutions to eliminate these effects.The results of experiments showed that the detection accuracy can reach up to 0.1mm for appearance parameters such as weld width and weld height,and as for weld angular distortion,the detection error can be controlled within 1°.In order to improve the detection accuracy,the stability of the detection environment should be ensured,interference from ambient light on the laser emitted by the sensor should be avoided,the cleanliness of the surface of the sensor's light-emitting and light-receiving should be sustained,the measured welds are supposed to be placed as horizontally as possible,and algorithm control parameters such as distance threshold L should be reasonably set as needs.Weld contour inspection results showed that the method of inspecting and evaluating the appearance quality of welds proposed in this paper can stably realize the intelligent inspection and evaluation of the appearance quality of butt welds and fillet welds,get relatively accurate detect results,and make great practical sense for ameliorating the welding process and improving the quality of welds. |
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