Belt conveyors are widely used due to their continuous and high-volume transportation characteristics. Longitudinal tears on the belt surface can lead to significant economic losses. Timely detection and handling are crucial for the safe and efficient operation of belt conveyors. This issue introduces "A New Generation of Online Detection Technology and Equipment for Longitudinal Tears in Conveyor Belts," which utilizes laser technology, image recognition technology, and conveyor belt dynamics to achieve all-weather, efficient online detection. Practical applications demonstrate that this technology and equipment are safe, reliable, and highly effective!

I. Research Background

Longitudinal tears in conveyor belts occur from time to time. A conveyor belt has approximately a 20% chance of experiencing a longitudinal tear after a routine inspection during its lifespan. Conveyor belts, which can be worth hundreds of thousands, or even millions of dollars, may be completely destroyed in a short period of time if a longitudinal tear occurs, resulting in significant economic losses. Even if repairable, it requires considerable manpower and time, significantly impacting normal production. In recent years, the use of conveyor belts and conveyors in China has increased significantly, expanding their applications and causing longitudinal tear incidents to become increasingly frequent.

Developing a reliable and practical monitoring device for longitudinal tears in conveyor belts has become both necessary and urgent. This allows for the timely detection and shutdown of conveyor belts experiencing longitudinal tears, minimizing losses. Domestic and international conveyor belt longitudinal tear monitoring devices come in various forms and types. They can be categorized into six major types: embedding method, contact method, exposure method, bandwidth detection method, ultrasonic detection method, and laser detection method.

Among these, the laser detection method uses a linear laser beam to continuously scan the belt surface. It leverages the characteristic that the laser beam undergoes severe deformation at the cracks caused by longitudinal tears to determine whether a longitudinal tear has occurred. A continuous straight line laser stripe is projected onto the bottom of the belt by a laser. After a high-speed camera acquires the belt surface image containing the line laser stripe, the computer extracts the stripe center and performs breakpoint detection on the centerline. When the comprehensive change characteristics of the laser stripe exceed the set threshold, it is considered that a longitudinal tear has occurred in the belt. This method is suitable for harsh environments, providing 24-hour uninterrupted automatic detection and judgment. It represents the latest technology in longitudinal tear detection.

II. Detection Device Principle

The laser 3D scanning conveyor belt longitudinal tear detection device (hereinafter referred to as the "device") utilizes laser technology, image recognition technology, and innovative conveyor belt dynamics technology. It overcomes the shortcomings of current longitudinal tear detection methods and can perform all-weather real-time online detection of the lower surface of the upper conveyor belt while the conveyor belt transporter is operating normally. Once a longitudinal tear occurs in the conveyor belt, an alarm will be issued immediately (within 1 second of detecting the longitudinal tear) and the conveyor belt will stop to prevent the accident from escalating.

The device uses optical triangulation and echo analysis principles for imaging, using non-contact measurement precision sensors to measure the width and depth of conveyor belt tear cracks. The laser emitted by the semiconductor laser is focused onto the object to be measured by a lens, and the reflected light is collected by the lens and projected onto the CCD. The signal processor calculates the distance information of the object to be measured by using trigonometric functions to calculate the position of the light spot on the CCD.

The laser and camera are installed on the lower left and right sides of the upper conveyor belt, respectively. The laser emits a strip-shaped laser beam to the bottom of the conveyor belt. After reflection from the surface of the conveyor belt, the camera collects the image and automatically extracts the center of the laser stripe. Based on the triangulation method, the height and depth parameters of the conveyor belt cross-section are analyzed and output in real-time to the control computer. After computer software analysis and data restoration, a 3D image of the bottom surface of the conveyor belt is obtained, which can visually determine whether a tear has occurred.

Based on the height and width of each abnormal point, the gap between other abnormal points, cross-sectional area, angle (coordinate value), contour, etc., it distinguishes between existing skin damage on the conveyor belt surface and cracks caused by longitudinal tears. The detailed group features accurately determine the depth, width, directionality, continuity, distribution regularity, and extension of the cracks, thereby judging whether a longitudinal tear has occurred.