New generation online inspection technology and equipment for lo
Update time：2023-03-13 11:17:40
The belt conveyor is widely used depending on the continuous mass transportation characteristics. The longitudinal tear of the belt surface may cause significant economic losses. Timely detection and treatment are important guarantees for the safe and efficient operation of the belt conveyor. The New Generation of On line Inspection Technology and Equipment for Longitudinal Tear of Conveyor Belt recommended by the Transformation Fruit in this issue uses laser technology, image recognition technology and conveyor belt dynamics technology to achieve all-weather online and efficient inspection. The practical application shows that this set of technology and equipment is safe and reliable, and the application effect is good!
1、 Research background
The longitudinal tear accident of conveyor belt happens frequently. The possibility of longitudinal tear of a conveyor belt after a routine inspection in its life cycle is about 20%. The conveyor belts worth millions of yuan or even more may be completely destroyed in a short time in case of longitudinal tear accident, resulting in huge economic losses. Even if it can be repaired, it also requires considerable manpower and time, which has a great impact on normal production. In recent years, the use of belt conveyors in China has become more and more large, and their application scope has become wider and wider, and the accidents of longitudinal tear have become more and more frequent.
It is very necessary and urgent to develop a reliable and practical monitoring device for the longitudinal tear of the conveyor belt, so as to realize the timely detection and shutdown of the longitudinal tear fault of the conveyor belt and minimize the loss. There are many forms and types of longitudinal tear monitoring devices for conveyor belts developed at home and abroad, which can be summarized into six types: embedded method, contact method, dew detection method, bandwidth detection method, ultrasonic detection method and laser detection method.
In the laser detection method, linear laser beam is used to continuously scan the belt surface, and the characteristics of serious deformation at the crack caused by longitudinal tear of the laser beam are used to judge whether the belt has longitudinal tear. The laser projects a continuous linear laser stripe to the bottom of the belt. After the high-speed camera obtains the image of the belt surface containing the linear laser stripe, the computer extracts the stripe center and detects the breakpoint of the stripe center line. When the comprehensive change feature of the laser stripe exceeds the set threshold, the belt is considered to have longitudinal tear. It is suitable for harsh environment, with automatic detection and judgment 24 hours a day. This method represents the latest longitudinal tear detection technology.
2、 Principle of detection device
The laser 3D scanning conveyor belt longitudinal tear detection device (hereinafter referred to as the "device") uses laser technology, image recognition technology and innovative conveyor belt dynamics technology to overcome the defects of the current longitudinal tear detection method. It can conduct real-time online detection of the bottom condition of the upper conveyor belt under the normal operation of the conveyor belt. Once the conveyor belt is longitudinally torn, An alarm will be given at the first time (longitudinal tear is detected for 1 second) and the conveyor belt will be stopped to avoid further expansion of the accident.
The device uses optical triangulation distance measurement principle and echo analysis principle for imaging, and uses non-contact precision sensors to measure the width and depth of conveyor belt tear cracks. The laser emitted by the semiconductor laser is focused on the object to be measured through the lens, and the reflected light is collected by the lens and then projected onto the CCD. The signal processor obtains the distance information of the measured object by calculating the position of the light spot on the CCD through the trigonometric function.
The laser and camera are respectively installed on the left and right sides of the upper conveyor belt. The laser emits a ribbon laser to the bottom of the conveyor belt, which is collected by the camera after the surface of the conveyor belt reflects, and the center of the laser stripe is automatically extracted. The height and depth parameters of the conveyor belt section are analyzed according to the triangulation method, and are output to the control computer in real time. Through computer software analysis and data restoration, the 3D image of the bottom of the conveyor belt is obtained. It can visually judge whether tearing occurs.
According to the height, width, gap, sectional area, angle (coordinate value), contour, etc. between each abnormal point and other abnormal points, distinguish the existing skin damage and cracks caused by longitudinal tear on the surface of the conveyor belt. Detailed group characteristics accurately determine the depth, width, directivity, continuity, distribution regularity, elongation, etc. of the crack, so as to judge whether longitudinal tearing occurs.