Telescopic Crane Research Articles

Hole-making and cutting effects on fatigue performance of ultra high strength steels

Ultra high strength steels provide opportunities for reduced-weight designs since they have higher tensile and fatigue strengths than the conventional mild steel grades. For typical applications such as telescopic cranes, tippers, chassis, and agricultural machinery, lower weight leads to lower fuel consumption and better road homologation. Before the start of their service life, steel components must be machined to their final shape as they are supplied in standardized shapes and sizes. Mechanical and thermal cutting strategies invoke various physical phenomena within the cut material affecting the in-use properties. The objective of this study is to quantify the effect of hole-making processes and edge-preparation on fatigue performance of ultra high strength steels. A series of fatigue experiments were conducted on steel grades with yield strengths from 700 to 960 MPa using axially loaded coupon samples with a hole manufactured by punching and laser cutting. Fatigue performance is compared to the detail categories provided by design standards. Additional tests under four-point bending loading were conducted to focus on flat edges machined by laser cutting and milling. Especially at high-cycle and infinite-fatigue lives, tested grades were superior to the typical design curves when the holes were punched with low clearance or laser cut.

Выбор гидравлической схемы для оптимальной работы забоечной машины

Blasthole stemming has a major impact on blasting operations. Depending on the stemming material, different types of equipment are used, one of which is described in this article. The article presents the ZM-7-G stemming truck manufactured by AZOTTEKH LLC, which is designed for mechanized stemming with loose material. The stemming truck complements a range of machines for mechanization blasting operations and improves the blasting efficiency, reducing the flyrock zone and enhancing the environmental situation in the quarry areas. An optimal hydraulic circuit is selected based on this model and taking into account the hydraulic fluid flow rate and pressure of the safety valves set to a specific value. Implementation of the hydraulic circuit with separated hydraulic fluid flows ensures efficient maintenance and economical consumption of the hydraulic fluid, correct operation of the crane with the rated capacity, as well as safe operation of all actuating mechanisms. Conclusions are made on operation of the telescopic crane with a clamp bucket, and a description of the selected hydraulic system is provided.

Machine-learning-based top-view safety monitoring of ground workforce on complex industrial sites

Telescopic cranes are powerful lifting facilities employed in construction, transportation, manufacturing and other industries. Since the ground workforce cannot be aware of their surrounding environment during the current crane operations in busy and complex sites, accidents and even fatalities are not avoidable. Hence, deploying an automatic and accurate top-view human detection solution would make significant improvements to the health and safety of the workforce on such industrial operational sites. The proposed method (CraneNet) is a new machine learning empowered solution to increase the visibility of a crane operator in complex industrial operational environments while addressing the challenges of human detection from top-view on a resource-constrained small-form PC to meet the space constraint in the operator’s cabin. CraneNet consists of 4 modified ResBlock-D modules to fulfill the real-time requirements. To increase the accuracy of small humans at high altitudes which is crucial for this use-case, a PAN (Path Aggregation Network) was designed and added to the architecture. This enhances the structure of CraneNet by adding a bottom-up path to spread the low-level information. Furthermore, three output layers were employed in CraneNet to further improve the accuracy of small objects. Spatial Pyramid Pooling (SPP) was integrated at the end of the backbone stage which increases the receptive field of the backbone, thereby increasing the accuracy. The CraneNet has achieved 92.59% of accuracy at 19 FPS on a portable device. The proposed machine learning model has been trained with the Standford Drone Dataset and Visdrone 2019 to further show the efficacy of the smart crane approach. Consequently, the proposed system is able to detect people in complex industrial operational areas from a distance up to 50 meters between the camera and the person. This system is also applicable to the detection of any other objects from an overhead camera.

Hybrid Welding (Laser-Electric Arc MAG) of High Yield Point Steel S960QL.

The article discusses the effect of the hybrid-welding process (laser–electric arc MAG Metal Active Gas) on the structure and properties of butt joints (having various thicknesses, i.e., 5 mm and 7 mm) made of steel S960QL. Welding tests were performed in the flat position (PA) and in the horizontal position (PC). Joints made of steel S960QL in the above-presented configuration are present in elements of crane structures (e.g., telescopic crane jibs). The welding tests involved the use of the G Mn4Ni1.5CrMo solid electrode wire and the Ar+18% CO2 shielding gas mixture (M21) (used in the MAG method). Non-destructive visual and radiographic tests did not reveal the presence of any welding imperfections in the joints. The welded joints obtained in the tests represented quality level B in accordance with the requirements of the ISO 12932 standard. Microscopic metallographic tests revealed that the heat-affected zone (HAZ) contained the coarse-grained martensitic structure resulting from the effect of the complex welding thermal cycle on the microstructure of the joints. Destructive tests revealed that the joints were characterised by tensile strength similar to that of the base material. The hybrid welding (laser–MAG) of steel S960QL enabled the obtainment of joints characterised by favourable plastic properties and impact energy exceeding 27 J. The tests revealed the possibility of making hybrid-welded joints satisfying the quality-related requirements specified in the ISO 15614-14 standard.

Maximizing Construction of Timber Kit Homes Using Telescopic Crane to Improve Efficiency and Safety: A Case Study

The challenges of improving efficiency and safety is a daunting task as workers are squeezed with an ever-dwindling resource pool and yet expected to deliver construction projects at optimum capacity. Improving efficiency and safety using telescopic cranes for the construction of Off-Site Manufacturing (OSM) timber kit homes is a viable option for the speedy delivery of new homes. An action research evaluated the maximization of the build and process efficiency and safety using a crane to erect wall panels, floors, and roofs. Data collection through direct observation assessed the labor uptime and downtime, including crane usage. A balanced score card was used by management for strategic organizational decision-making regarding the crane erection. The use of the crane reduced workplace manual handling of OSM panels, minimized the exposure of operatives to work at height risks, and eliminated alterations to scaffolds. However, the manual loading of thermal-insulated plasterboards to floor decks impacted the process efficiency and speed of installing the fixtures and increased the risk of musculoskeletal disorders. High labor downtimes were associated with the adverse weather conditions, which slowed the efficiency of the workforce during construction. The management’s inability to adequately plan the work program further hindered aspects of lifting operations and the speed and number of houses built.

Nomination of controls of various layouts for heavy machinery.

Control selection in heavy machinery may be a problem due to the poor compatibility of the commonly-used single line of vertical levers for controls. This study examined the effects of control arrangements on directional compatibility and participant responses in terms of choice/function of controls. We investigated experimentally, for a number of new designs of control arrangements, the selection of controls for requested functions of four different machines: fork lift trucks, excavators, tower cranes, and telescopic cranes. Control arrangements were designed with different levels of directional compatibility and participants were requested to nominate which control was related to each of the machine motions and to make ratings of certainty of response. A second part required participants to rank the various control arrangements in terms of their compatibility. The in-line control arrangement was worst for each machine and increased directional compatibility improved the stereotype strength, certainty of response and ranking of control arrangement. Directional compatibility is the main factor in the design of control/machine output arrangements due to its effect on stereotype strength and correct selection of control of a given function.

Enseñanza del diseño mecánico mediante un proyecto CAD documentado

In mechanical project development, there are two kind of knowledge, theoretical, taught according on syllabus at universities, and in the other hand, practical, usually learned in the working environment. For graduated recently engineers, it means a disadvantage once they are trying to get a job. Seeking to achieve better results on student performance from a real design plane, learning strategy is presented to enhance both knowledges applying them to an educational project completed, learning topics that normally is not covered on syllabus and generating all information required about design and manufacturing project. This paper shows a case of study about a telescopic crane design, analyzing all information generated from conceptual to detail engineering. Finally, preliminary results about all information generated through the different project stages is presented, helping in this way the decision-making process of the students and the information management when developing project from the beginning to the end.

Analytical method comparison on critical force of the stepped column model of telescopic crane

The calculation of the critical force of the stepped column model of telescopic boom crane is the key to stability calculation of all-terrain crane. In slightly bending theory, differential equation can be built up, and then the deflection curve of ideal column can be obtained. Using this curve and the Rayleigh–Ritz method, the Euler force of the ideal column can be obtained. For n-stepped columns, Euler forces and the effective length coefficients can be acquired using the deflection curve of the ideal column and parabolic curve, respectively, combined with the Rayleigh–Ritz method. Differential equations of the n-stepped telescopic boom are established based on the vertical and horizontal buckling theory. The recursive formula of the stability of the n-stepped telescopic boom is deduced by the mathematical induction method. For the transcendental equation in the recursive formula, combined with the structural force characteristics and supplementary formulas, the Levenberg–Marquardt numerical optimization algorithm is used to solve the equations with n unknowns. Length coefficients obtained by the three methods are compared using GB3811-2008 and ANSYS 17.0. The results show that the accuracy of the numerical algorithm is the highest, and the first two algorithms will produce large errors when the stepped columns have more steps.

Dynamic Model Studies of Telescopic Crane with a Lifting and Pulling Load Movement

This paper presents a kinematic and dynamic model which can be used to simulate telescopic crane slewing, luffing, telescoping, lifting and pulling load movements. The crane joint motion can be described as smooth continuous sine cosine function. The crane dynamic equations are derived by Lagrange method. The lifting rope length from boom tip to hooks described as a time-variant constraint equation. The dynamic equations and the constraint equation form differential algebraic equations which can be solved by constraint stabilization method. The validity and correctness of the telescopic crane model is verified through an example. We prospect the model can be used for the research on compound motion control and lifting scheme design of telescopic crane in the virtual reality.

Modeling and Simulation of Telescopic Rotary Crane

Modeling and Simulation of Telescopic Rotary Crane

The Steiner Formula and the Polar Moment of Inertia for the Closed Planar Motions in Complex Plane

In this paper, the Steiner area formula and the polar moments of inertia were expressed during one-parameter closed planar motions in complex plane. The Steiner points or Steiner normal concepts were described according to whe-ther rotation number was different from zero or equal to zero. The moving pole point was given with its components and its relation to the Steiner point or Steiner normal which was specified. The Steiner formula and the polar moments of inertia were expressed for the inverse motion. The fixed pole point was calculated for the inverse motion. The sagittal motion of a tele-scopic crane was considered as an example. This motion was described by a double hinge consisting of the fixed control panel of the telescopic crane and its moving arm. The results obtained in the first section of this study were applied to this motion.

On the Kinematics for the Closed Planar Homothetic Inverse Motions in Complex Plane

In this paper, the Steiner area formula and the polar moment of inertia were expressed during one-parameter closed planar homothetic inverse motions in complex plane. The Steiner point was defined when the rotation number was different zero and it was called the Steiner normal when the rotation number was equal to zero. The fixed pole point was given with its components and its relation between Steiner point or Steiner normal was explained. The sagittal motion of a telescopic crane was considered as an example. This motion was described by a double hinge consisting of the fixed control panel of the telescopic crane and the moving arm of the telescopic crane. The theoretical concepts and results were applied for this motion.

Modelling and optimisation of an 8 × 8 heavy duty vehicle's hydro-pneumatic suspension system

In this paper, modelling of the hydro-pneumatic suspension (HPS) system of a heavy duty vehicle that has all-wheel steering and driving capability is studied. The prototype vehicle of concern is a mobile telescopic crane. The spring and damper effects of the HPS, which is used generally in heavy commercial vehicles and in military vehicles, have been modelled separately. First, HPS dynamics is studied on 1/8 vehicle model and then vehicle dynamics is examined on the MSC ADAMS/Car model. HPS of the prototype vehicle is assessed by some objective functions. In addition, simulation-based optimisation is performed using a 1/8 vehicle model. Various designs are obtained and their performances are compared with that of the prototype vehicle's HPS by the ADAMS/Car model simulations. Modelling and optimisation studies reveal a sound background to improve the prototype vehicle and to design active HPS system.

Influence of flexibilities of cranes structural components on load trajectory

Building computational models of cranes requires using of simplifications. Frequently accepted simplification is ignoring deformations of structural components. At the same time there is no appropriate study concerning estimation of the influence of flexible crane components on the movement of a load. In the paper, the influence of flexibilities of seven crane structural components on working accuracy in relation to the trajectory of the load has been estimated. Numerically efficient telescopic crane model has been developed with the use of the finite element method. Beside of qualitative analysis used in other works to evaluate the results, a method of quantitative analysis proposed by the author has been applied. The analyses show that based on computational models one can make proper assessment of a load motion. The condition is a proper selection of considered flexible components. A parametric identification and/or quantitative assessment should be a criterion of models configuration.

The Influence of Clearances in a Drive System on Dynamics and Kinematics of a Telescopic Crane

Abstract The paper presents the results of numerical analyses that were carried out in order to evaluate how a change in a size of a clearance in a slewing motion drive system of a telescopic crane influences the movement of a load and the dynamic loads of a structure. A computational model was developed based on a real structure of an experimental crane by using the ADAMS software. The analyses showed that a circumferential clearance at the output of a reduction gear, which is less than 1º, does not adversely affect the precision of the load movement. An excessive clearance leads to losing fluidity of a body slewing motion and to changes in the trajectory of the load.

The Kinetic Energy Formula for the Closed Planar Homothetic Inverse Motions in Complex Plane

In this paper, the kinetic energy formula was expressed during one-parameter closed planar homothetic inverse motions in complex plane. Then the relation between the kinetic energy formula and the Steiner formula was given. As an example the sagittal motion of a telescopic crane was considered. This motion was described by a double hinge consisting of the fixed control panel of telescopic crane and the moving arm of telescopic crane. The results were applied to experimentally measured motion.

Dynamics of telescopic cranes with flexible structural components

Today׳s crane numerical models are devoid of some of the simplifications that were used in the past. These changes primarily take into account flexibilities of those structural components that used to be treated as non-deformable. Consequently, various studies analyse the same working movements based on different models.The paper presents ten variants of a computational model for a telescopic boom crane that differs in number and selection of flexible components. It has been analysed how the above-mentioned differences affect the correctness of mapping the dynamic properties of real structures via their computational models. Modelling and numerical simulations were conducted using the finite element method. The compatibility of the numerical simulation results and test results of a real structure was qualitatively and quantitatively assessed. Time characteristics and frequency characteristics after application of the discrete Fourier transformation were analysed. The analyses showed that the parameters of the modified components should be determined by taking into account their interactions with their surroundings in order to ensure correctness of the solutions. A comparison of the shape and position of spectral lines with respect to changes in the overall flexibility of the models facilitates in deciding which components should be modified and which should be omitted in order to correctly imitate the dynamic properties of a real structure.

Finite Element Analysis of the Boom of Crane Loaded Statically

In this paper, the finite element analysis was carried out on boom of telescopic crane using ANSYS package software and the manual calculation as well as the analysis by the strength of materials procedure. The stress picture along the boom model was conducted under the maximum load carrying capacity. The stress developed at the interception of hydraulic rod with the first tube is higher than that developed along the rest of the boom. Moreover, the maximum deflection occurs at the boom head sheave. In order to investigate the accuracy of the results, a comparison between the two approaches and the exact obtained by the strength of materials procedure is carried out. Although the high capabilities of ANSYS software, the results are somewhat less accurate than that obtained by the manual calculations. Besides that, the results obtained by the finite element manual calculations are wholly similar to that of strength of materials procedure. Model taken for this paper is TADANO TR-350 XL 35-ton capacity.

DYNAMIC BEHAVIOR OF TELESCOPIC CRANES BOOM

Telescopic cranes are usually steel beam systems carrying a load at the tip while comprising at least one constant and one moving part. In this work, an analytical model suitable for the dynamic analysis of telescopic cranes boom is presented. The system considered herein is composed — without losing generality — of two beams. The first one is a jut-out beam on which a variable in time force is moving with constant velocity and the second one is a cantilever with length varying in time that is subjected to its self-weight and a force at the tip also changing with time. As a result, the eigenfrequencies and modal shapes of the second beam are also varying in time. The theoretical formulation is based on a continuum approach employing the modal superposition technique. Various cases of telescopic cranes boom are studied and the analytical results obtained in this work are tabulated in the form of dynamic response diagrams.

Lift Path Planning for Telescopic Crane Based-on Improved hRRT

Lift Path Planning for Telescopic Crane Based-on Improved hRRT