Research on quality inspection for backside weld of tailored blank laser welding based on texture feature
In tailored blank laser welding, the quality of backside weld has a significant influence on mechanical properties of tailored blanks. The conventional method for the quality inspection of weld seams is based on the structured light deformation. However, the structured light deformation is not obvious in the backside weld which with dust disturbance, so the extraction of feature points is difficult only based on the structured light. A quality inspection system for backside weld of tailored blank laser welding was built and a new method based on combination of texture feature and structured light was proposed in this paper. In this method, the textural feature of the image was firstly analyzed, and then the image was segmented by the difference of the image texture feature between the weld region and the base metal region; finally, the zone of the weld were recognized based on voting strategy and the feature points were extracted. Experiments were conducted with this method, then the considered weld width was detected and other weld defects could also be detected. The experiment results showed that the proposed inspection system and method were effective for backside weld quality inspection of tailored blanks laser welding.
Welding bead and chamfer inspection by means of laser vision
12 In this paper an inspection system for both weld quality and chamfer quality is presented which is a 3D laser vision system using principles of optical triangulation, and is composed of sensor head and controller. Sensor head includes laser diode, micro CCD camera, filter and some mirrors. This system can be used in welding bead inspection (including undercut) and chamfer inspection as well. Compared with conventional inspection method, it is much more convenient to use and the inspection time is to be greatly shortened. Data saved in PC can be used for statistics afterwards. This system has been being used in Koje Shipyard or Samsung Heavy Industries and the need is being increased.
A new mixed chain sampling plan based on the process capability index for product acceptance
ABSTRACT This article proposes a new mixed chain sampling plan based on the process capability index Cpk, where the quality characteristic of interest follows the normal distribution with unknown mean and variance. The advantages of this proposed mixed sampling plan are also discussed. Tables are constructed to determine the optimal parameters for practical applications. In order to construct the tables, the problem is formulated as a nonlinear programming where the objective function to be minimized is the average sample number and the constraints are related to lot acceptance probabilities at acceptable quality level and limiting quality level under the operating characteristic curve. The practical application of the proposed mixed sampling plan is explained with an illustrative example. Comparison of the proposed sampling plan is also made with other existing sampling plans.