When large banana screen is used, it is easy to crack or even break, which brings huge economic loss to the coal washing plant. In order to diagnose banana screen girder cracks, change post-maintenance to preventive maintenance, and even predict the life of banana screen, this paper presents a vibration based crack fault diagnosis method for large banana screen girder. An experimental model is designed to study the characteristic frequency variation of the vibration response when cracks appear. Field experiments show that this method is feasible and effective, and has high application and popularization value.
Large banana screen is widely used in coal washing plants and mines because of its large screening area and high screening efficiency (up to 0%). However, it is found that the girder of banana screen is prone to cracks or even fractures during long-term use, and steel plates are often used to repair it in the field, but practice has proved that the girder can only maintain a short time after repair before breaking again. This type of banana screen is imported, and the replacement of a beam must be ordered from abroad, and the order time is as long as two months, during which the repeated maintenance costs are very high and seriously affect the production, bringing huge economic losses to the coal washing plant. Therefore, how to diagnose banana screen girder cracks, change post-maintenance to preventive maintenance, and even estimate the life of banana screen is urgent. The girder of the banana screen at work is completely covered by screen plate, coal, etc., and the girder itself has a protective rubber layer up to 10mm thick, so it is impossible to diagnose whether it has cracks by conventional means. Based on the theory of vibration testing, a new diagnosis method based on vibration is proposed, and a banana screen experimental model is designed to study this method in detail. The field verification shows that this method is feasible and effective. Experimental design of banana screen girder crack diagnosis
The banana screen used in the field is mainly composed of exciter, screen frame, large beam (6 bottom beams, one upper support beam, and one screen frame support beam before and after), screen plate, spring assembly and support, etc. The amplitude is 11mm, the motor speed is 880pm, the size of the screen body is 6100mm×4200mm, which is a large equipment. In this experiment, the attachments on beams such as sieve plates were simplified, the 6 girder were simplified into two, and the front and rear support beams were simplified, while the upper support beams were retained. The key components of the experimental research, one or two bottom beams, are consistent with the original banana screen, and their size is reduced to one-sixth of the original. Instead of the shaker, the force hammer generates the exciting force, and the spring assembly is redesigned according to the principle of simulating the original banana screen amplitude.