Research On Visual Inspection Method Of Inner Surface Defects Of Aluminum Alloy Seamless Gas Gylinder

The detection of inner surface defects of aluminum alloy seamless gas cylinders is one of the key links to improve the competitiveness of enterprises and the production process.In the past,the gas cylinder defect detection method mainly used endoscope for multi-angle observation,which not only had low accuracy,but also could not meet the requirements of the production line.Many domestic and foreign researchers try to solve this problem through nondestructive testing technology,but there are certain limitations and the real-time on-line testing effect is not ideal.Now,as a new detection technology,machine vision is very suitable for detecting defects on the inner surface of gas cylinders.The research on defect detection of gas cylinders in China is still in its infancy,which has affected the competitiveness of China's products in pressure vessels.In this paper,a series of key problems in the on-line inspection of inner surface defects of aluminum alloy seamless gas cylinders will be studied by visual inspection.Firstly,according to the structure and size characteristics of aluminum alloy seamless gas cylinder,this topic carries out the research of hardware system,and designs the inner surface defect detection system of gas cylinder.The difficulty in this part lies in the selection of cameras.It is difficult for ordinary industrial cameras to enter the inside of the gas cylinder for imaging.Considering that the contact image sensor,which is often used in scanners,has a small external dimension and is easy to enter the inside of the gas cylinder.Therefore,this system adopts the contact image sensor designed by Valin Optoelectronics Company.The lateral resolution is calculated according to the longitudinal resolution of the sensor,and the camera support structure is designed so that the camera can extend into the cylinder to collect images.The hardware system is mainly divided into two parts.One is a translation table and a camera support structure carried by the translation table,which can realize longitudinal movement relative to the inner surface of the gas cylinder.The second is the cylinder rotating device,which can realize lateral movement relative to the inner surface of the cylinder.Finally,the communication function between PLC controller and computer is used to realize the coordinated movement of the two units and detect the inner surface of the whole cylinder.Secondly,based on the image processing software Halcon,this topic designs the detection algorithm of stretch damage,pit and scratch defects of gas cylinders.According to the imaging characteristics and differences of various defects,the algorithm can extract the target area and eliminate pollution through image preprocessing,Gaussian line detection and threshold segmentation.Based on VS2012,MFC human-computer interaction interface is designed to ensure that users can adjust relevant parameters and realize serial communication,detection result display and other functions.Finally,thread function is used to solve the problem that serial communication,defect detection and result display run simultaneously.Through many experimental tests,the experimental results all prove that the inner surface defect detection system of aluminum alloy seamless gas cylinder can quickly and stably detect stretch damage,pits and scratches on the inner surface of the gas cylinder.