The failure of the slewing support leads to significant economic damage associated with long downtime of equipment due to the impossibility of replacing it with a new one as a result of the ...imposition of sanctions by unfriendly countries. If earlier, before the introduction of restrictive sanctions (measures), the failure of the was less painful and took from 15 days to one month maximum, now it stretches to 3… 5 months. One of the reasons for the failure of equipment is the wear of the teeth of the wheel and gear of the rotary bearing, which leads to a change in the stress-strain state of the cassettes with rolling elements. There is uneven wear of the wheel in height, with the upper part of the wheel wearing out to a greater extent than the lower part, which leads to slippage between the gear teeth in the upper part to a greater extent than in the lower part. Wear of the teeth of the gear and the turntable leads to uneven and increased wear of the cassettes and cages of the slewing support and, accordingly, to the loss of rolling elements. The established unevenness of wheel wear in its various segments makes it possible to make proposals for improving the wheel design. The studies of the wear of cassettes and rollers made it possible to establish changes in the stress-strain state in the contact zone of the cassette and the roller, which in the future will improve the method of their calculation and make a proposal to improve the connection between the cassette and the roller.
This research reports the results of both the implementation of innovative materials, such as composite material, and the application of the prestressing technique through appropriate tie-rods, for ...crane construction. The novelty lies in the introduction of both factors in order to reduce and limit the vertical deflection, while also reducing the cross section, which is the main constraint at the machine design phase. In this way, to limit the load-induced deflection of the crane, a constant external action is applied that induces a deflection opposite to that induced by the load. In particular, the object of this research is a jib crane with dimensions 4000x5000 (height and length in mm) with a load capacity of 4905 N. The research involves analytical dimensioning followed by verification of the results obtained using finite elements software (Ansys®). The parameters adopted for sizing, both the boom and the column, are the maximum displacements and safety coefficients concerning both maximum stresses and buckling phenomena. The main result is that the composite crane has the lowest weight: approximately 29 % and 21 % of the weight of the corresponding non-prestressed steel crane, for non-prestressed and prestressed composite configurations, respectively. The last part of the research concerns the construction methods for building cranes, in particular the implementation of the composite solution.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The vibration analysis of a jib crane was investigated using the method of vibration analysis of frame structures. This approach is theoretically based in order to derive the governing equations of ...vibration for the system. The jib crane was treated as a frame structure with the mast and jib taken as independent frame structures. The resulting frame structures were then treated as beams that conform to Euler-Bernoulli beams in order to analyse their vibration properties. Amplitude of vibration, the first three natural frequencies as well as the first three mode shapes were calculate using this approach as well as the response of the system. The theoretical approach was derived to accommodate all standard sets of natural frequencies and mode shapes of the jib crane from the established boundary conditions. This was developed by an assumed mode method and incorporated a single mode expansion for the developed system. The effect of the load carried by the jib crane was taking into consideration which constitutes a harmonic force on the jib with addition of moment of this force to the mast. The resulting theoretical general equations from the single mode approach were then used to evaluate the vibration parameters of the jib crane using numerical values.
•A fuzzy robust facility layout problem is described.•Cranes are considered in the plant region.•Two proposed meta-heuristic algorithms were used to solve the problem.
Facility layout problems are ...defined as the placement of facilities in a plant region. In this paper a facility layout problem was clarified by the facility dimensions and the materials flow between facilities are uncertain as fuzzy random variables and the plant region was equipped with the wall mounted jib cranes and the small gate cranes and there were some forbidden areas in the plant region where the placement of facilities were forbidden. The objective functions of the problems have been contemplated as minimizing materials handling cost of the operators and the cranes and for the first time maximizing cranes usability of wall mounted jib cranes and small gate cranes by calculating their covered area on the facilities. To solve the problem a multi-objective population-based on simulated annealing algorithm (MPS) and a Modified Non-dominated Sorting Genetic Algorithm II (MNSGA-II) was proposed then six case studies were solved by them. The results reveal that run time of the MNSGA-II for large size problems are better than the MPS algorithm and the MPS algorithm finds better solutions with materials handling cost of the operators and the cranes and the MNSGA-II finds better solutions with cranes usability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Material handling operations give rise to Euler and Coriolis forces whose impacts should be minimized already at the stage of selection of the system parameters and mechanism structure. Effective ...optimization, confirmed by dynamic analysis, allows the dynamic overload values to be significantly reduced at the stage of design of the steel structure, resulting in a lighter and cheaper structure. Basing on the mathematical model the optimization criteria were formulated in the form of quadratic functionals for each crane mechanism. Solving the functionals to find the minimum values yields a set of optimal parameters of mechanisms such that their interactions should be optimal. The innovative feature of the presented solution is a comprehensive approach to optimization of multi-drive systems, targeting the vibration reduction of the load suspended on the hook and minimizing forces acting in the ropes. Optimization tasks should be executed independently, in the specified order resulting from feedback interactions between respective mechanisms. This approach paired with the method of selective analysis of mechanisms structures will be further developed into the method of synthesizing globally optimal configurations of interacting mechanisms.
•The impacts of Euler's and Coriolis's forces on crane dynamics should be minimized by selecting the mechanisms parameters.•Rope blocks positions in the compensation system determine the amplitudes of the hook trajectory during luffing.•Force acting in the winch rope and the power demand depend on the parameters of all interacting mechanisms.•Optimization criteria can be combined, but only in relation to one specific mechanism.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper represents a continuation of the issue of the technical solution of the mast-type jib crane for handling sludge pumps. It is situated and used in building no. 900, block V2 of Jaslovské ...Bohunice nuclear power plant. It accounts for an optimization of the original, in operation damaged handling equipment with manual control of lift and rotation. The overload of the equipment has a negligible effect on the lifting force on a crank. It was ascertained that the lifting force still belongs to the recommended range of 120 N to 160 N for comfortable operation by one worker. Due to the fact that in the original design there is a complete absence of bearings in the rotating mechanism, it is the solution to this problem that is on the subject of the paper. The difficulties with lifting the pumps from sludge ambient, which occurred during the use of the mast jib crane, in a way opened the door to further design modifications to the original structure. As a solution, it is proposed to cancel the original construction of the carrier inserted into the support and replace it with a fixed mast on which the jib would rotate. In this way, on the one hand it would potentially be conceivable to increase the load capacity and thus solve the problem of lifting pumps attached to the bottom of a tank. On the other hand, it is also attainable to amplify the scope of action of this crane.
Precise luffing of payload in mobile cranes is a crucial part of material handling and safety in industrial operations. Explosive ordnance disposal uses a bomb disposal robot to safely disable ...explosive devices at a safe distance. This robot is a mobile jib crane type with a gripper as an end effector instead of the typical suspension cable with a hook. The common challenge of this crane type is the arm/jib movement sensitivity with respect to tip-over stability of the crane body. This is directly influenced by the payload and constrained by the degree of freedom. This paper presents a control strategy of the joint for luffing such that the back wheels remain in contact with the surface ground and avoid bucking at any given instance of weight change in the payload. Fuzzy logic was applied to control the motor torque and luffing angle of the arm in response to the load and gripper opening size to maintain the tip-over stability margin at the highest value possible. The response curves at different configurations of the two input signals were also analyzed based on the rules set to determine its precision with respect to the expected response curve.
Through the corrective maintenance process of a bearing, regardless of its origin, certain anomalies related to its main elements, due to the condition of the type of maintenance, are expected. This ...was the case of the jib crane of the Caribbean Submarine fleet, used mainly to load the wiring and charging sockets for the supply of electrical energy to the Submarines. During a routine operation, it malfunctioned and stopped working without warning. An inspection was carried out in which corrective maintenance was deemed necessary, it was at the time that the bearing support was uncovered and its advanced state of deterioration was observed. Being this the main failure, and through application of engineering principles and simulation software, the reason for the deterioration was determined, and the optimal bearings for the correct operation of the jib crane were selected.
Durante el proceso de mantenimiento correctivo de un rodamiento, independiente de su origen, se espera encontrar ciertas anomalías relacionadas con sus elementos principales, esto debido a la condición del tipo de mantenimiento. Este fue el caso del brazo de carga de la Flotilla de Submarinos del Caribe, utilizado principalmente para cargar el cableado y la toma de carga en el suministro de energía eléctrica a los Submarinos. Durante una operación rutinaria presentó fallas y dejó de funcionar sin dar previo aviso. Se llevó a cabo una inspección en la que se determinó que era necesario realizar un mantenimiento correctivo, fue en el momento en que se destapó el soporte de los rodamientos que se evidencio el avanzado estado de deterioro de estos, siendo esta la falla principal y mediante aplicación de los principios de ingeniería y software de simulación, se logró determinar la razón del deterioro y seleccionar los rodamientos óptimos para el correcto funcionamiento del brazo de carga.
Presents the results of statistical analyses identified by the expert diagnostics of defects of the self-propelled lifting jib cranes, spent a normative term of exploitation. The greatest number of ...defects associated with the destruction and dete-rioration of structural elements, the occurrence of fatigue cracks and a violation of the conditions of operation of the equipment. The greatest number of defects occurs in the hydraulic system of cranes, the rope-block system, and rarely in steel structures. To conduct risk analysis of self-propelled jib cranes in case of insufficient information, proposed the method of expert estimations. It allows to assess the impact of potential defects on self-propelled jib cranes on the value of the economic damage of the crane and moving cargo and the value of the traumatic exposure on men. The proposed list of possible defects self-propelled lifting jib cranes and a checklist of questions about the degree of influence of these defects. Proposed calculated dependences to the approximate calculation of the magnitude of technical risk in the opera-tion of self-propelled jib cranes. The results of statistical analysis of expert estimations for each possible defect and per-formed their ranking in terms of impact on the magnitude of the economic damage of the crane and moving loads, the value of the traumatic exposure. Was calculated the value of technical risk for the surveyed taps.
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