Multidimensional Data Interpretation of Vibration Signals Registered in Different Locations for System Condition Monitoring of a Three-Stage Gear Transmission Operating under Difficult Conditions

This article provides a discussion of the results of studies on the original system condition monitoring of a three-stage transmission with a bevel–cylindrical–planetary configuration installed in an experimental scraper conveyor. Due to the high vibroactivity of gear transmissions operating under the impact of a scraper conveyor’s chain drive, these unwanted effects of machine operating vibrations were assumed to be applied. For purposes of the study, vibrations were measured on the driving transmission housing in an idling scraper conveyor. The main purpose of the study was to establish the frequencies characteristic of the gear transmission, and to determine whether it was possible to run vibroacoustic diagnostics of the same transmission under conditions with a considerable impact of the conveyor chain. An additional cognitively significant research goal was the analysis of the dependence of the diagnostic utility of the signal depending on the sensor mounting point. Five different locations of three-axis sensors oriented to the next stages and various types of gears were determined, as well as places characterized by high spatial accessibility, which are often selected as places for measuring the vibration of gears. Using MATLAB software, a program was written that was calibrated and adapted to the specifics of the measuring equipment based on the collected test results. As a result, it was possible to obtain a multidimensional data interpretation of vibration signals of system condition monitoring of a three-stage gear transmission operating under difficult conditions. The results were based on signals registered on the real three-stage gear transmission operating under the impact of a scraper conveyor’s chain drive.

Study on the mechanical effect and wear behaviour of middle trough of a scraper conveyor based on DEM–MBD

Middle trough is the main-force portion of a scraper conveyor during transport, and its performance directly affects the reliability and service life of the scraper conveyor. To investigate the wear of a middle trough, a coupling-wear model of a middle trough was built to analyse the motion state and stress of a scraper, and the wear of the middle trough was analysed according to the wear morphology of the middle plate. The research results demonstrated that the simulation model based on coupling of the discrete element method and multi-body dynamics could effectively simulate the transport conditions of a scraper conveyor. The wear of the middle trough was mainly caused by three-body wear. Formation of three-body wear required that the coal particles between the scraper (chain) and middle plate must be in a certain position and posture, and the coal particles were subjected to the normal force of the scraper (chain) and middle plate. Constant fluctuation in the movement and force of the scraper (chain) resulted in uneven wear of the middle trough and random occurrence of three-body wear. This study provides a theoretical basis for wear prediction of the middle trough of a scraper conveyor and a simulation basis for further research on the wear resistance of a middle trough.

Response Analysis of a Scraper Conveyor under Chain Faults Based on MBD-DEM-FEM

To tackle the difficulty in obtaining the response data of chain and bulk coal under chain faults, this paper uses a new method for the fault simulation of scraper chains based on the coupling of multi-body dynamics (MBD), discrete element method (DEM), and finite element method (FEM). With the force and stacking angle as response values, the contact parameters of bulk coal were revised using a rotary transport test. The simplified DEM-MBD model was verified from the resistance using the point-by-point method. The static structure model of the chain was verified by the chain tensile experiment. The DEM-MBD coupling results show that when the chain is stuck or broken, the dynamic properties of the chain and bulk coal fluctuate sharply, and the wear of the medium plate increases. Based on the DEM-MBD coupling results and the DEM-FEM unidirectional coupling, the stress, strain and life were acquired, and were verified experimentally. Regarding the fracture, the Plackett-Burman test was used to determine that the crack depth, initial angle, and tensile load significantly affect the stress intensity factor (SIF). The quadratic model between significant factors and SIF was constructed using the response surface method, which provides a reference for the simulation of the scraper conveyor, the fault mechanism, and the optimization of the design of the chain.

Optimized Design of Mechanical Chain Drive Based on a Wireless Sensor Network Data Algorithm

In this paper, we use a wireless sensor network data algorithm to optimize the design of mechanical chain drive by conducting an in-depth study of the mechanical chain drive optimization. We utilize the crowdsourcing feature of the swarm-wise sensing network for assisted wireless sensor networking to achieve crowdsourcing-assisted localization. We consider a framework for crowdsourcing-assisted GPS localization of wireless sensor networks and propose two recruitment participant optimization objectives, namely, minimum participants and time efficiency, respectively. A model and theoretical basis are provided for the subsequent trusted data-driven participant selection problem in swarm-wise sensing networks. The sprocket-chain engagement frequency has the greatest influence on the horizontal bending-vertical bending composite in different terrain conditions. The dynamic characteristics under working conditions are most influenced, while the scraping of the scraper and the central groove significantly influenced horizontal bending and vertical bending. Under load conditions, the amplitude of the scraper and central groove scraping increases significantly, which harm the dynamics of the scraper conveyor. By monitoring the speed difference between the head and tail sprockets and the overhang of the scraper, the tensioning status of the scraper conveyor chain can be effectively monitored to avoid chain jamming and chain breakage caused by the loose chain, thus improving the reliability and stability of the scraper conveyor.

Reliability and maintainability of scraper conveyor used in coal mining in the Jiu Valley

Purpose.The aim of the study is to determine and analyse causes of faults in the operation of TR-7A scraper conveyor and to estimate the required time for their remediation and select the methods of their prevention and elimination. Methods. The characteristic of a system, such as the scraper conveyor, intended to fulfil its specified function in time and operation conditions, can be studied, theoretically, by determining its operational reliability. This implies the existence of a framework that incorporates several interconnected components of technical, operational, commercial and management nature. The quantitative expression of reliability was based on elements of mathematical probability theory and statistics (exponential distribution law), failure and repair mechanism not being subject to certain laws. Findings. The following TR-7A subassemblies, if defective, could have been the cause of a failure: chains, hydraulic couplings, chain lifters, drive, return drums, some electrical equipment. After 28 months of monitoring the TR-7A operation, we have established the number of failures (defects) ni, the operating time between failures ti, frequency of failures fc, time to repair tri, weight repair time pr, mean time between failures (MTBF), mean time to repair (MTR). Originality.Data collection and processing involves the adoption of specific procedures to allow the correct highlighting of the causes and frequency of failures. The accomplishment of this approach allowed finding the solutions for increasing reliability of some subassemblies of TR-7A conveyor (i.e., those subjected to abrasive wear). Practical implications.One solution was to use materials with compositional and functional gradient in the case of worn surfaces of some subassemblies. It was successfully applied for the chain lifters where a significant increase in the mean time between failures was obtained. The field of application of these materials can be extended to the metal subassemblies of machines and equipment with abrasion wear that occurs both in underground mines and in quarries.

Time-dependent reliability and optimal design of scraper chains based on fretting wear process

Purpose This paper aims to present a dynamic reliability model of scraper chains based on the fretting wear process and propose a reasonable structural optimization method. Design/methodology/approach First, the dynamic tension of the scraper chain is modeled by considering the polygon effect of the scraper conveyor. Then, the numerical wear model of the scraper chain is established based on the tangential and radial fretting wear modes. The scraper chain wear process is introduced based on the diameter wear rate. Furthermore, the time-dependent reliability of scraper chains based on the fretting wear process is addressed by the third-moment saddlepoint approximation (TMSA) method. Finally, the scraper chain is optimized based on the reliability optimization design theory. Findings There is a correlation between the wear and the dynamic tension of the scraper conveyor. The unit sliding distance of fretting wear is affected by the dynamic tension of the scraper conveyor. The reliability estimation of the scraper chain with incomplete probability information is achieved by using the TMSA for the method needs only the first three statistical moments of the state variable. From the perspective of the chain drive system, the reliability-based optimal design of the scraper chain can effectively extend its service life and reduce its linear density. Originality/value The innovation of the work is that the physical model of the scraper chain wear is established based on the dynamic analysis of the scraper conveyor. And based on the physical model of wear, the time-dependent reliability and optimal design of scraper chains are carried out.