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.

Influence of orientation of zones of higher hardness of composite layers on their resistance to wear

Purpose: Experimentally substantiate the influence of the orientation of zones of higher hardness on the wear mechanism of contact surfaces. Design/methodology/approach: Forming of variable composition within the working surfaces of parts is a common way to solve the problem of uneven wear. The tests were aimed at determining the characteristics of the layers surfaced with the orientation of the zones of high hardness. For this different tests and measurements were done. Before the test, samples of 45 steel were surfaced with a preliminary application of titanium carbide paste. Findings: As a result of researches it was found that different ways of the orientation of zones of higher hardness have different influences on the characteristics of a surface. The main conclusion is that the transverse orientation of such zones helps to increase the wear resistance of the surface and to save its original relief. Research limitations/implications: The roughness, wear resistance, zonal hardness, and relief of layers surfaced with the orientation of zones of higher hardness were studied. Practical implications: The results obtained are useful in the field of rolling production and mechanical engineering to avoid the uneven wear of parts and as a result to extend the term of their exploitation. Originality/value: In this paper the model concepts of wear process of surfaces with variable composition and measurements of characteristics of surface considering its local hardening are proposed.

Tension force equalizer in a rope system using a proximity sensor

Different values of tension forces in the load-bearing ropes of elevators, which push the rope into the grooves of the traction discs with different pressure, are the cause of uneven wear of the grooves of the traction discs under operating conditions. Current technical standards in the EU stipulate that the load suspended on load-bearing ropes be evenly distributed to all ropes used, using one of the many construction designs for tension force equalizers in the rope system. The main subject and primary objective of this paper are to present the construction design, 3D model and produced device of one of four produced prototypes, which were constructed in the “Research and Testing Laboratory”, and allow setting of differing values of tension forces in the system of ropes of a traction elevator, to values of the same size. Laboratory measurements were performed on the produced device, which enables the detection of tension forces in ropes and the magnitude of these forces in the required period to be graphically displayed on a PC. The prototype tension force equalizer can show the functionality and practical applicability of the procedure of balancing the levels of tension forces, which are of unequal strengths at the start of the laboratory measurement.

Analysis of structures of flat planting machines

One of the methods of material processing is considered, which allows to obtain high geometric accuracy and low surface roughness of parts, namely their abrasive finishing. The high quality of machining of parts in this way is due to the use of coordinated relative movement of the workpiece and the cutting tool. According to the kinematic features, most lapping machines can be divided into two groups: machines with oscillating working motion and machines with rotating lapping motion. The machines of the first group are more common due to the simplicity of their design and versatility. However, the possibility of their use is limited by the size range of the workpieces and uneven wear of the cutting tool and, as a consequence, the uneven surface treatment of the part. The machines of the second group are considered the most versatile, as they allow processing a wide range of parts, varying in shape and size, but they are also not without such a disadvantage as uneven wear of the cutting tool with all the corresponding consequences. Improving the efficiency of abrasive finishing by complicating the trajectory of the relative movement of the tool and the part, ie the formation of a unique mutual working movement of the lapping and the movement of the workpiece, is one of the most common areas. The main disadvantage of equipment that provides processing of parts on this principle is, in most cases, limited regulation of the operating parameters of the cutting process, so this area remains promising and has broad prospects for development. The constructive scheme of the hydraulic-pulse flat-lapping machine offered in work thanks to a combination of advantages of the hydraulic-pulse drive with use of numerical program control will allow to provide unique mutual multi-movement of preparation and the lapping tool with a possibility of adjustment of its parameters in the course of processing. Purposeful choice of the shape and density of the trajectory of the working movement of the tool will form a micro relief of the treated surface with the necessary statistical parameters and low roughness.

Rigidity of telescopic boom equipment

As a result of the study, analytical models of the rigidity of the telescopic boom equipment in the vertical and horizontal planes were developed, which take into account: the influence of uneven intersectional vertical and horizontal gaps, the flexibility of the sliding supports, the flexural rigidity of the sections, the rigidity of the telescoping hydraulic cylinder and the lifting hydraulic cylinder. The dynamic coefficient is determined, taking into account the presence of intersectional gaps, with unsteady movement in the vertical and horizontal plane. The influence of intersectional gaps on the coefficient of dynamism and rigidity of the boom equipment taking into account the uneven wear of the sliding supports is established. Keywords telescopic boom, railway crane, stiffness coefficient, dynamic coefficient

CHARACTERISTICS OF THE PARTS MATERIAL WITH VIBRATION HARDENING

The analysis of the work of tillage machines is carried out, the reasons for the failures of their working bodies (plowshares) during operation are revealed. Research has been carried out on the change in the characteristics of the material of the cutting elements of soil-cultivating machines after vibration hardening, as well as the effect of hardening on the strength of restored plow shares. The parameters of vibration hardening of plow shares are experimentally determined. Microstructural studies were carried out in order to reveal the influence of the processing method on the properties of the plowshares material. Criteria for the limiting state of plowshares are revealed. Bench tests of plow shares at the installation allow you to adjust the intensity of their wear. It has been established that the depth of wear of the ploughshare material is the most significant geometric parameter affecting its resource. Experimental studies have established the values of the main parameters of vibration hardening: the frequency and amplitude of oscillations of the working working tool and the hardening time. The values of the degree of hardening of the material of the cutting edge of the reconditioned plow shares have been determined. The relationship between the values of the change in the width of the ploughshare and the thickness of its blade during deformation has been established. It was found that, in addition to the processing modes, the shape of the processing tool affects the geometry of the share. An uneven wear pattern along the length of the share is revealed. The results of changes in the wear along the width of the cutting element and the intensity of its wear depending on the operating time are given. It has been established that the amount of wear of the plowshare cutting element depends on the technological modes of processing and the material. Conducted bench studies of the specified variants of plowshares in order to check the operational reliability of the restored and vibration-hardened plow shares. It was found that the plowshares made of 65G steel, treated by vibration hardening, had the lowest wear rate, which is explained by the change in the structure of its material during vibration hardening.

Wear Problems of High-Speed Wheel/Rail Systems: Observations, Causes, and Countermeasures in China

Wear problems of wheel/rail systems occurring on the Chinese high-speed railway network in the last decade are summarized and explained together with the corresponding experience of treating them. Focus is placed on uneven wear because even wear is not an urgent issue due to its very low wear rate for the Chinese high-speed railway systems. Two typical problems of longitudinal uneven wear, namely, wheel polygonization and rail corrugation, are introduced in terms of their characteristics, consequences, causes and initiation mechanisms. Next, wheel hollow wear and flange/gauge side wear, as typical problems of lateral uneven wear, are similarly discussed. Validated countermeasures against all these problems are presented at the end of this paper together with further proposals under testing or consideration. This work is principally based on first-hand data collected from field observations, monitoring tests and dynamic measurements, but typical numerical approaches and results are also presented to help explain the observed phenomena.