Companies that use belt conveyors in their transport systems aim to achieve highly productive and reliable systems, while concurrently ensuring efficient transport of material over large distances. Due to the need to provide high strength of conveyor belt joints and to guarantee their fail-safe use, the author has designed a computer system for on-site monitoring. The aim of this system is to achieve long life and high reliability of conveyor belt joints by using effective methods for diagnosing their condition. The system can find applications as real-time monitoring in mines, to predict the moment of potential joint breakup and to avoid it as a result of proper control. In Poland, the system will also be used by companies that produce belts and joints to analyze the strength of their products under real-world dynamic conditions.
The fact that typical belt joints made by cold bonding have both strong and weak points has been frequently ignored. Bonding technologies are recognized as the best methods of belt-connecting because they guarantee belt integrity, have high strength and durability, and such joints pass easily over the conveyor's rollers and drums. Although bonded joints are relatively inexpensive, they have a considerable strength differential, caused by various temperature and moisture conditions prevailing when the belt is bonded.
No less important is the variable joint quality that may be achieved when bonding in unfavourable conditions such as in underground mines. As a result, conveyor belt joints often break without any early warning of the upcoming damage. An unplanned belt breakage may result from mechanical blocking, side deviation of the belt or drum soiling. In such situations, the machine operators may prevent breakage if they observe a problem and respond quickly enough; however, this is not an effective method to prevent joint breakage. Taking into consideration both the nature and the conditions of typical belt conveyor operation, there is a need to develop a reliable monitoring system intended to prevent belt breakage, which will signal when a break is likely about to occur. This goal may be achieved through continuous measurement and analysis of the elongation of a belt's bonded joints during operation. An appropriate monitoring system was designed and constructed to accomplish that goal.
The monitoring system has been mounted on one of the division haulage conveyors operating at the LW Bogdanka coal mine in Poland. The technology allows for a signal to be sent warning of conditions that could lead to belt failure in the area of the joint. As well, system add-ons can extend the data analysis including, for example, a review based on measurements in real conditions of the durability of various types of bonded conveyor belt joints in order to improve their quality.
Monitoring can also allow a practical comparison of the properties of adhesives used regarding their ply strength and shear strength. The system currently being tested and the accompanying software allows for the visualization of changes in the length of a specific joint during operation, in the length of each belt sector between the joints and the collective presentation of those values for all joints in a conveyor, and all belt sectors between the joints. It is also possible to statistically analyze the values registered and to export measurement data, graphics, etc.
Bearing in mind the fact that belt conveyors are commonly used in industry and that there are no other effective monitoring or control systems to predict breakage, it may be concluded that the results obtained in our studies will not only contribute to the increase of the knowledge and experience related to the operation of belt conveyors but will also limit losses caused by stoppages resulting from unplanned failures.
Dr. Dariusz Mazurkiewicz is at the Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland. He can be contacted at firstname.lastname@example.org. The studies were financed from the funds of the Polish State Committee for Scientific Research in 2004-07 as a research project.