Showing papers on "Slewing bearing published in 2015"

A new finite element approach for the analysis of slewing bearings in wind turbine generators using superelement techniques

Abstract: Several analytical models have been proposed to estimate the load distribution and the deformation of slewing bearing assemblies in wind turbine generators (WTGs). Even though they are a useful tool for designers as a first approach, most of them assume rigid rings and rigid supporting structures, leading to inaccurate results; even if compliance is considered in some models, only certain boundary conditions can be taken into account, and their complex and diverse nature make often these models inaccurate. For this reason, WTG manufacturers need costly FE analyses to obtain results adapted to the particular geometries and operational conditions of their yaw and pitch bearings assemblies. In this sense, this work presents a superelement-based FE model that significantly reduces the computational cost with a negligible accuracy loss.

Running Torque of Slow Speed Two-Point and Four-Point Contact Bearings

Abstract: A decoupled slow speed friction torque model has been developed to predict the running torque of a double-arched angular contact bearing when operating as a four-point, as well as a two-point contact bearing. The load distribution model from Amasorrain et al. (2003) and the kinematics model developed by Leblanc and Nelias (2007) have been combined after ignoring centrifugal and gyroscopic effects, a valid assumption for slow speed operation. Results from the model are compared with previous literature data, as well as with tests done on a specially-developed friction torque rig. The comparison with the literature results was done for two specific cases: (i) when only one out of the two contact lines in the four-point contact bearing is active (effectively creating a two-point contact bearing); and (ii) where both contact lines in the four-point contact bearing are active. Further, the comparison was done with a custom-built friction torque rig with FAG QJ309 bearings, again for two cases: (i) bearings mounted with a specific clearance (two-point contact); and (ii) bearings mounted with larger size balls to obtain interference (four-point contact). All tests were performed at low speeds. The sliding friction, which is an important input to the friction torque model, is carefully measured on ball-on-plate test using the same interface roughness, speed and contact pressure conditions as seen in the QJ309 friction test. The model comparison with experimental results is covered. The comparison is found to be encouraging, with the RMS difference being less than 7% between the model and experimental data for a four point contact.

Method and apparatus for detecting and monitoring states

Abstract: The invention relates to a state-detecting and state-monitoring system (100) for the at least temporary, possibly periodic, preferably even permanent, value-, signal-or data-based acquisition and monitoring of state parameters of at least one assembly (K) or component, or even sub-elements of this assembly or component, in particular at least of a bearing or a rotary connection, for example in or on a wind turbine, and also relates to an associated method, characterized by: at least one, preferably more than two, contact sensor(s) (3) attached to or incorporated in the subassembly (K) or component, preferably which can be attached or incorporated directly or indirectly, can for example be attached or incorporated at an incorporating location (A), in particular at or on a planar or rounded surface (1) or contour of this assembly (K) by means of screwing/inserting/welding/brazing/adhesive bonding or clamping in the vicinity of a bearing ring in a wind turbine, preferably of a nose ring or support ring or retaining ring of a slewing bearing, alternatively which can be attached or can be incorporated directly at or on at least one inner or outer surface of a blade, main or tower bearing of a wind turbine.

On-line large slewing bearing residual life prediction method based on multi-dimensional data drive

Abstract: The invention discloses an on-line large slewing bearing residual life prediction method based on multi-dimensional data drive. The method includes the steps of firstly, conducting a full-life fatigue test on a slewing bearing, and obtaining multiple sets of vibration acceleration signal monitoring data of the whole test cycle of the slewing bearing; secondly, decomposing a vibration signal into a plurality of intrinsic mode functions (IMFs) through ensemble empirical mode decomposition (EEMD), and selecting a plurality of IMFs which can reflect performance degradation of the slewing bearing for signal reconstruction through principle component analysis (PCA) so that the aim of filtering noise elimination can be achieved; thirdly, conducting PCA on multi-dimensional acceleration signals at different stages and signals of the initial period of the test so as to obtain one-dimensional continuous SPE (C-SPE), reflecting the change situations of the multi-dimensional acceleration vibration signals on the basis of the one-dimensional C-SPE, calculating multiple time domain characteristics of the C-SPE, and establishing a performance degradation model of the slewing bearing. The method is few in manual intervention process, and the prediction result is closer to the engineering practice.

Shaper capable of automatically measuring slewing bearing deviation from circular form

Abstract: The invention discloses a shaper capable of automatically measuring slewing bearing deviation from circular form. The shaper comprises an electrical vortex sensor, a clamping hydraulic system, a shaping hydraulic system, a rotating table system and a PLC control system; after the self-centering work of the clamping hydraulic system is completed, the electrical vortex sensor 15 mounted on a frame 22 moves to a detection position along a linear guide rail 20 mounted on a support 16; a rotating table 2 is driven by a servo motor 23 to rotate by 360 degrees so that the position, having the maximum value of the deviation from circular form, of the slewing bearing 1 to be shaped can be detected by the electrical vortex sensor 15. The shaper capable of automatically measuring slewing bearing deviation from circular form is capable of automatically detecting the circularity and automatically rounding; in other words, the electrical vortex sensor is used for accurately measuring the slewing bearing deviation from circular form, a hydraulic cylinder is applied to pressurizing instead of manual work, and the shaping work of the slewing bearing is completed under the control of the PLC control system. The method is capable of remarkably improving the detection accuracy and the production efficiency, realizing automation, and liberating labor from complex shaping work.

Experimental Study of Four-Point Contact Ball Bearing with Deformable Rings

Abstract: When a ball bearing is designed with thin rings or is mounted in a flexible housing, the assumption of rigid rings is not true anymore. In this article, an experimental study is presented and a comparison with a numerical model is performed. The numerical approach is based on the coupling between a semi-analytical code and a finite element (FE) model that computes the deformation of the rings and housings. The numerical model accounts for ring ovalization, raceway opening, change of conformity, and structural displacements of the whole assembly. The experimental setup allows investigation of the load–displacement behavior of a four-point contact ball bearing submitted to a static thrust loading. Displacements are measured by an optical method (stereo-correlation) that enables comparison of the surface deformation of the two tested bearings and computation of the rigid-body displacement of the inner ring with respect to the outer ring. A comparison between experimental results, numerical results, with and ...

Residual useful life prediction of large-size low-speed slewing bearings – a data driven method

Abstract: In this paper, a data driven method based on Ensemble Empirical Mode Decomposition-Principal Component Analysis (EEMD-PCA) and Least Square-Support Vector Machine (LS-SVM) is proposed to achieve residual useful life (RUL) prediction for slewing bearings. Firstly, life-cycle vibration signals are acquired and divided into several signal segments, and EEMD is then utilized to decompose each segment into Intrinsic Mode Functions (IMFs). Afterwards, PCA is introduced to illustrate the trends of each IMF across the life cycle, and some of the IMFs that contribute to reveal the performance degradation process of the slewing bearing are selected to reconstruct and de-noise the vibration signals. After that, continuous squared prediction error (C-SPE) and its features are presented as performance degradation indicators. Finally, an RUL prediction model is built on the basis of the indicators using LS-SVM. The results of a life-cycle experiment show that the C-SPE of the de-noised vibration signals can precisely explain the performance degradation process of the tested slewing bearing and that the established RUL prediction model is close to practice. Besides, a comparison study shows that the C-SPE based RUL prediction model is more efficient and accurate than the signal based model. Therefore, the proposed method ensures high-reliability slewing bearing prognostics.

A life test method and result analysis for slewing bearings in wind turbines

Abstract: Slewing bearings generally consist of the rotational connection between two substructures and are usually used for complex load at very low speeds. If the slewing bearing has some faults during the...

Dynamic Carrying Capacity Analysis of Double-Row Four-Point Contact Ball Slewing Bearing

Abstract: Carrying capacity is the most important performance index for slewing bearings. Maximizing the carrying capacity of slewing bearing is one pursuing goal for the bearing designer; this is usually realized by optimizing the design parameters. A method of analyzing the carrying capacity of double-row four-point contact ball slewing bearing by using dynamic carrying capacity surfaces was proposed in this paper. Based on the dynamic load carrying capacity surface of the slewing bearing, the effect of changes of the bearing design parameters, such as axial clearance, raceway groove radius coefficient, and contact angle, on the dynamic carrying capacity of the slewing bearing was researched; the trend and the degree of the effect of the micro changes of the bearing design parameters on the dynamic load carrying capacity of the bearing were discussed, and the results provide the basis for optimizing the design parameter of this type of slewing bearing.

Intelligent health evaluation method of slewing bearing adopting multiple types of signals from monitoring system

Abstract: Slewing bearing, which is widely applied in tank, excavator and wind turbine, is a critical component of rotational machine. Standard procedure for bearing life calculation and condition assessment was established in general rolling bearings, nevertheless, relatively less literatures, in regard to the health condition assessment of slewing bearing, were published in past. Real time health condition assessment for slewing bearing is used for the purpose of avoiding catastrophic failures by detectable and preventative measurement. In this paper, a new strategy was present for health evaluation of slewing bearing based on multiple characteristic parameters, and ANN (Artificial Neural Network ) and ANFIS(Adaptive Neuro-Fuzzy Inference System ) models were demonstrated to predicted the health condition of slewing bearings. The prediction capabilities offered by ANN and ANFIS were shown by using data obtained from full life test of slewing bearings in NJUT test System. Various statistical performance indexes were utilized to compare the performance of two predicted models. The results suggest that ANFIS-based prediction model outperforms ANN models.

Spiral lifting mechanism and automatic guided vehicle (AGV)

Abstract: The invention discloses a spiral lifting mechanism and an automatic guided vehicle (AGV). The spiral lifting mechanism comprises a jacking plate, an installation base board, a jacking mechanism and a jacking drive mechanism. The jacking mechanism comprises a thread pair and a slewing bearing, the outer ring of an outer thread part of the thread pair is a gear, the inner ring is in threaded connection with an inner thread part of the thread pair, the inner ring of the slewing bearing is fixedly connected with the installation base board, the outer ring of the slewing bearing is fixedly connected with the lower portion of the inner thread part of the thread pair, and the jacking plate is fixed to the outer thread part of the thread pair. The jacking drive mechanism comprises a lifting pinion and a lifting drive motor; the lifting pinion is fixedly connected with a motor shaft of the lifting drive motor; the lifting pinion is engaged with an outer-ring gear of the slewing bearing; the lifting drive motor is installed on the installation base board. The spiral lifting mechanism further comprises a rotary control mechanism, and the rotary control mechanism can rotate and lock the outer thread part of the thread pair.

The effect of manufacturing tolerances on the load carrying capacity of large diameter bearings

Abstract: This paper deals with simplified 3D finite element (FE) analysis on the effect of manufacturing tolerances on the load carrying capacity of large diameter bearings based on Hertz theory. The nonlinear connector elements are used to model the rolling elements. This model enables us to evaluate the contact load on the rolling elements with relatively reduced calculation time. FE study has been carried out by allocating tolerance on balls and raceways using Monte Carlo simulation technique. The variation in dimension on balls is taken as per IS 2898-1976. A coding has been developed and employed for Monte Carlo simulation. Using the results of Monte Carlo simulation, tolerance has been assigned to the elements of large diameter bearing. From the results of finite element analysis, it is identified that analysis of large diameter bearing with tolerance on ball and raceway will lead to safe design.

Slew bearing early damage detection based on multivariate state estimation technique and sequential probability ratio test

Abstract: This paper presents the application of multivariate state estimation technique (MSET) and sequential probability ratio test (SPRT) for early damage detection of low speed slew bearing. This paper also investigates the appropriate and reliable features for slew bearing condition monitoring. It is found that largest Lyapunov exponent (LLE), approximate entropy, margin factor (MF) and impulse factor (IF) are able to monitor the slew bearing condition. The aim of present study is to calculate single condition monitoring parameter from multiple features. Combined MSET and SPRT were used to analyse the recorded reliable features obtained from a previous work. The result shows that the method can clearly picked up the sign of early bearing damage.

Rotating lifting appliance for crane

Abstract: The invention discloses a rotating lifting appliance for a crane. The rotating lifting appliance comprises a trolley body, a lifting drive motor, a reduction gearbox, two groups of duplex winding drums, four groups of lifting components, a lifting hanging beam and a rotating hanging beam, wherein each of the two groups of duplex winding drums is connected with the corresponding two groups of lifting components; each group of lifting component comprises a first fixed pulley, a second fixed pulley and a movable pulley; the four groups of lifting components form a statically indeterminate structure, so that shake produced by the lifting appliance during the using process can be reduced; a slewing bearing is arranged between the lifting hanging beam and the rotating hanging beam; the lifting hanging beam is fixedly connected with an inner ring of the slewing bearing; the rotating hanging beam is fixedly connected with an outer gear ring of the slewing bearing; a rotating component is fixedly connected onto the lifting hanging beam and is used for driving the outer gear ring of the slewing bearing, so as to reduce the manpower burden and improve the use safety of the lifting appliance. A lifting hook is rotatably connected to the middle position of the lower surface of the rotating hanging beam, a plurality of magnetic lifting appliances are symmetrically distributed on the rotating hanging beam on the two sides of the lifting hook, so that sufficient reliability is provided for the lifting work of bar materials.

Driving -steering mechanism

Abstract: The utility model discloses a driving -steering mechanism for crane cart's running gear, driving -steering mechanism install on the tyre iron, and driving -steering mechanism passes through the connected to the frame of last flange and cart, and this driving -steering mechanism includes slewing bearing, worm gear reducer and motor. Install on the tyre iron slewing bearing's outer lane. Worm gear reducer installs on the tyre iron, and worm gear reducer's top is connected to the flange, and worm gear reducer's snail worm and wheel meshes, and worm gear reducer's worm wheel is installed on slewing bearing's outer lane. The motor is connected with worm gear reducer's worm. Motor drive worm gear reducer's worm is rotated, and rotate the outer lane that drives worm wheel and slewing bearing, realizes turning to. This driving -steering mechanism simple structure, light in weight, axial dimensions are little, are applicable to lower automobile body, also can reduce the totality height of hoist simultaneously. This driving -steering mechanism makes and installation cost hangs down small and exquisite flexibility.

Vibration and acoustic emission-based condition monitoring and prognostic methods for very low speed slew bearing

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Slewing bearing device for a wind turbine

Abstract: A slewing bearing device (14) for a wind turbine (100) for attaching a wind turbine blade (10) to a rotor hub (12) rotatably includes: an outer race fixed to the rotor hub; an inner race fixed to the wind turbine blade; a plurality of rolling elements disposed between the outer race and the inner race; and a force receiving part fixed to the rotor hub (12) or formed integrally with the rotor hub (12), the force receiving part being configured to receive force transmitted from an outer circumferential surface of the outer race when the outer race is about to deform outward in a radial direction of the outer race.

FEM Model for Friction Moment Calculations in Ball-Raceway Contacts for Applications in Four Contact Point Slewing Bearings

Abstract: This work is a first step in FE modeling of friction moment in slewing bearings due to microslip. To this end, a multiparametric ball-raceway model has been built to map the friction moment due to one-ball sector of the bearing, in order to integrate it later in a load distribution model developed previously by the authors. Parameters as ball diameter, osculation ratio, mean diameter, and initial contact angle are considered, as well as radial and axial interferences to approximate the friction moment of a bearing sector.

Reversing device for automotive seat assembly

Abstract: The utility model provides a reversing device for automotive seat assembly. The reversing device comprises a fixed bottom plate, a rotating bottom plate, an overturning frame, a supporting rod, linear guide rails and guide rail sliders, wherein the rotating bottom plate is connected with the fixed bottom plate through a slewing bearing, two ends of the supporting rod are fixed on the overturning frame and the rotating bottom plate respectively through fulcrums with rotating shafts, and the guide rail sliders are fixed on the overturning frame and can slide on the linear guide rails. The reversing device for automotive seat assembly enables reversing and rotation of an automotive seat to be achieved through tools, so that fatigue degree of operators is lowered greatly, and working efficiency is improved substantially.

Direct shear test system for anisotropy of geosynthetics and implementation method of direct shear test system

Abstract: The invention discloses a direct shear test system for anisotropy of geosynthetics and an implementation method of the direct shear test system The direct shear test system comprises a test bed rack, a slewing bearing, a dial, a lower shearing box, an upper shearing box, a vertical loading device, a horizontal loading device, a guide rail, a displacement sensor, a slewing bearing control device and a bearing plate, wherein the guide rail and the displacement sensor are arranged on the test bed rack; the dial and the slewing bearing control device are respectively arranged on the slewing bearing; the vertical loading device is arranged on the slewing bearing sequentially through the bearing plate, the upper shearing box and the lower shearing box; the lower shearing box is driven to rotate by the slewing bearing; the cross section of a geosynthetic which needs to be subjected to a shear test is round, and the diameter of the geosynthetic is same as the outer diameter of the lower shearing box; the horizontal loading device is connected with the slewing bearing and can slide on the guide rail According to the direct shear test system for the anisotropy of the geosynthetics, the technical problem that the engineering practice cannot be truly reflected by the interface mechanical characteristics of the geosynthetics and fillings which are obtained in the test in the prior art is solved

Laser cutting machine and closed detection method thereof

Abstract: The invention discloses a laser cutting machine which comprises an industrial robot and a laser cutting assembly The laser cutting assembly is installed at the tail end of the industrial robot through a laser cutting assembly installation seat and comprises a linear sliding table and a laser cutting head The laser cutting head is installed on the linear sliding table The linear sliding table is installed on the laser cutting assembly installation seat through a slewing bearing The mechanical axis of the laser cutting head and the center line of the slewing bearing are coaxial A mark point locating visual sensor is further arranged on the slewing bearing The invention further discloses a closed detection method based on the laser cutting machine of the structure The laser cutting machine is simple in structure, the laser axis incapable of being measured is converted into the mechanical axis capable of being measured, the position of the axis of a polished shaft is determined, closed detection can be finished in the trial cut process, efficiency is high, the number of rejected products can be effectively reduced, and cost is reduced

Experimental Study on Acoustic Emission Detection for Low Speed Heavy Duty Crane Slewing Bearing

Abstract: By use of the custom-built crane model, AE instrument and loads, a large amount of experiments have been done. For all AE signals acquired from the slewing bearing with no defect and with defect on different operation mode, AE signal parameter distribution analysis, AE signal parameter correlation analysis, AE signal frequency spectrum analysis have been achieved. The AE parameter distribution range for signals acquired from the slewing bearing with defect is much wider than that for those from the slewing bearing with no defect. By observing energy–duration correlation diagram, the defect signal can be identified evidently. Through frequency spectrum analysis, it can be found that the defect will lead to high frequency signal. In addition, the statistical analysis method is used to investigate the AE characteristics of the non-defective slewing bearing and defective slewing bearing. The statistical results of AE parameters are obtained respectively under different load and rotation speed of slewing bearing. Hits sum and energy sum of AE signal acquired from the slewing bearing with defect are much higher than the values acquired from the slewing bearing with no defect, and they increase with loads increasing. The maximum amplitude, hits sum, energy sum of AE signal acquired from slewing bearing with defect are all higher than those acquired from the slewing bearing with no defect regardless of rotation speed.

Slewing bearing mills tooth cooling system

Abstract: Slewing bearing mills tooth cooling system includes through connections's air supply device, dehumidifier, air-fuel mixture device and jet-propelled pipe in proper order, and does the oil tank of air-fuel mixture device fuel feeding, the air-fuel mixture device includes the hybrid tube, and the hybrid tube is middle thin and structure that enlarge to both ends from top to bottom gradually, is provided with the air-supply line that extends to hybrid tube inside in the top center of hybrid tube, be provided with on the lateral wall of hybrid tube upper end with said oil tank intercommunication advance oil pipe, be provided with flow control valve on advancing oil pipe, the lower extreme of hybrid tube is connected with a plurality of jet-propelled pipes, spouts tracheal end fixing down near the milling cutter of milling machine upright. The utility model discloses a ventilated mode, it is pollution-free, saved and carried out the trouble handled to the cutting fluid, in the wind that blows off, increased a small amount of atomizing oil, play lubrication action, air-fuel mixture device simple structure, convenient to use.

Slewing bearing test bench

Abstract: The utility model discloses a slewing bearing test bench belongs to slewing bearing inspection test bench technical field. The utility model discloses in, be equipped with initiative slewing bearing at the upper surface of base, initiative slewing bearing's inner circle and base fixed connection, and initiative slewing bearing links to each other with actuating mechanism, and this actuating mechanism drives initiative slewing bearing and is rotary motion, be equipped with the cab apron in initiative slewing bearing's top, initiative slewing bearing's outer ring gear and the lower fixed surface who crosses the cab apron are connected, and the slewing bearing's that awaits measuring inner circle and the last fixed surface who crosses the cab apron are connected. The utility model discloses in be rotary motion through actuating mechanism drive initiative slewing bearing to driving the inner circle of being surveyed slewing bearing and rotating, and apply different load to it through loading device, the performance parameter when bearing different load with simulation tests slewing bearing under the normal service condition changes, and the test result is accurate, the slewing bearing's that can guarantee to await measuring safety and reliability service.

Rotatory hoist of hoist

Abstract: The utility model discloses a rotatory hoist of hoist, including dolly automobile body, lift driving motor, reducing gear box, two sets of pair reel, 4 lifting unit of group, lift hanging beam and rotatory hanging beam, every pair reel is connected with two sets of lifting unit, and every lifting unit of group includes first fixed pulley, second fixed pulley and movable pulley. 4 the lifting unit of group forms hyperstatic structure, and what reduce to produce in the hoist use rocks. Be provided with slewing bearing between lift hanging beam and the rotatory hanging beam, lift hanging beam and slewing bearing's inner circle fixed connection, rotatory hanging beam and slewing bearing's outer ring gear fixed connection, fixed connection has the rotating assembly of the outer ring gear of drive slewing bearing on the lift hanging beam to alleviate the manpower burden, increase the safety in utilization of hoist. The intermediate position of the lower surface of rotatory hanging beam rotates and is connected with the lifting hook, and the symmetric distribution has a plurality of electromagnetism hoists on the rotatory hanging beam of lifting hook both sides, provides abundant reliability to the slinging work of rod.

Slewing bearing machining and heat treatment process

Abstract: The invention discloses a slewing bearing machining and heat treatment process. The slewing bearing machining and heat treatment process comprises the steps of charging, rough machining, QPQ (Quench-Polish-Quench) complex salt bath treatment, roller path quenching and fine machining. A process program is simplified, the cost is reduced, the hardness, the abrasion resistance, the corrosion resistance and the fatigue resistance are improved, the deformation amount is small, the yield is improved, indexes of parts can be optimized, and the slewing bearing machining and heat treatment process is easy to popularize and use.

Hydraulic suspension heavy-load transportation vehicle

Abstract: The invention provides a hydraulic suspension heavy-load transportation vehicle. The hydraulic suspension heavy-load transportation vehicle comprises a vehicle body, an axle and wheels; a slewing bearing is arranged on the vehicle body; the slewing bearing comprises an inner ring and an outer ring; the inner ring and the outer ring are capable of rotating relatively; the outer ring is horizontally fixed on the vehicle body; a supporting seat is fixed in the inner ring; the vehicle further comprises a steering system; the steering system comprises a front wheel group and a rear wheel group; the front wheel group and the rear wheel group are driven by a steering hydraulic cylinder, respectively; the steering hydraulic cylinder is horizontally mounted on the vehicle body and hinged to a stirring crank arm; the stirring crank arm is fixedly connected to the top surface of the supporting seat; the supporting seat rotates along with the slewing bearing so as to drive the wheels to rotate; for steering, the wheels of the front wheel group all are deflected in the same direction, while the wheels of the rear wheel group all are deflected in other direction; the wheels of the vehicle run in the same moving trajectory, and therefore, the all-wheel steering of the vehicle is realized. The hydraulic suspension heavy-load transportation vehicle is capable of meeting the requirements of large logistics transportation due to a small turning radius and flexible turning; meanwhile, the cost is also reduced and the production efficiency is improved.