Cutter design and multi-objective optimization of machine for cable peeling is proposed to use mechanical peeling instead of manual peeling in this paper. First, the design of the machine for cable peeling includes executive mechanism, driving part for cable, driving part for executive mechanism, and peeling mechanism. Then, the cutting experiment platform is set up to verify the actual effect of cutting, and different cutting depths, cutting speeds and fixing cables methods are discussed by the cutting experiment platform. A numerical simulation method is proposed, and different cutting methods, cutting depths and cutting speeds for cutting different materials are discussed by simulation method. The results show that simultaneous cutting is better than sequential cutting. The results show a good agreement between the results obtained from the finite element modelling and experimental investigations. A theoretical reference is provided for subsequent structural improvement. Finally, multi-objective optimization of machine for cable peeling is realized. The aim of the optimization was improving the dimensional accuracy after cutting and reducing the deformation of the cut surface. Cutter thickness, cutter angle, and cutter material are used as optimization variables, and the final optimal solution is obtained. The cutter is manufactured according to the final optimal solution, experiment of cutting is performed, and good agreements were achieved between optimal solution and experiments. Comparing the final results with the initial results shows a significant improvement.
This study is mainly about the optimization, simulation and experiment of a Counter-rotation Straw Returning Cultivator (CSRC), aiming at the problems that the existing CSRC has serious entanglement of grass, terrible jam of soil, large energy consumption, and poor straw coverage rate. Besides, an optimized Rotary Blade Roller (RBR) and a device to avoid the jam of soil were designed to optimize CSRC. A discrete element simulation model of straw-soil-RBR was established based on the EDEM software. The optimization simulation experiment of 4 factors and 3 levels, which took the single-blade operation width, bending angle, advance speed and rotation speed of RBR as factors, and used the straw coverage rate and power consumption as evaluation indicators, was carried out to optimize the structure parameters and working parameters of the RBR with the method of orthogonal experiment. The simulation experiment results showed that the optimal combination of parameters of the RBR at the tillage depth of 130 mm were 237.58 r/min of RBR rotation speed, 1.11m/s of forward speed, 35 mm of single-blade working width, and 134.09° of bending angle. Field tests showed that the straw coverage rate was 89.29%, the average torque was 517.25 N·m, the soil fragmentation rate was 83.21%, and the flatness of the surface after cultivation was less than 4 cm under the conditions of optimal parameters mentioned above. Therefore, the CSRC perfectly satisfied the industry standards, and meet the design requirements of machinery.
The present paper describes a method for determining geometries of gear-honing wheels used in the final process for manufacturing automotive transmission gears. Inappropriate geometries of gear-honing wheels could cause large undulations on finished gear-tooth flanks, and the finished gear would be out of the required accuracy. In such cases, the geometries of gear-honing wheels are required to be modified iteratively until the finished gears have sufficient accuracy. The change in meshing stiffness of a gear-honing wheel and a finished gear significantly affects the rotational synchronization. The poor rotation synchronization could cause the large undulation on a finished gear-tooth flank, to be different from the target micro geometries. This paper presented a geometrical approach that was proposed for a determination method of gear-honing-wheel geometries. The method allows the meshing stiffness to be balanced. Gear-honing wheels designed with the proposed method induced the desired micro geometries of finished gear-tooth flanks in gear-honing experiments. Therefore, the proposed method with the geometrical approach could be useful for the determination of gear-honing-wheel geometries.
This research aims to provide a novel nanofluid / minimal lubrication (MQL) technology for 7075-T6 aluminum alloy microdeep drilling. This technology will extend the life of tools used for precision machining. A parameter combination meeting the optimal quality-related objectives was obtained, and a predictive model was developed. Because microdrilling force and torque were two quality-related objectives, this study adopted Taguchi’s robust design, used machining parameters (i.e., nanofluid weight percentage concentration, spindle speed, feed rate, nozzle distance, nozzle angle, MQL flow, air compression, and pecking depth), and performed grey relational analyses to obtain the parameter combination generating the optimal microdrilling force and torque. Subsequently, this study used a neural network and conducted Taguchi grey relational analyses (where Taguchi orthogonal tables were used as the experimental basis and the experimental data from grey relational analyses were used as training examples) to develop a highly accurate microdrilling predictive model. The parameter combination for generating the optimal microdrilling force and torque predicted differed from those of the experiment results by only 0.44% and 1.24%.
There are lots of general parts with frequent maintenance and high interchangeability for continuous casting machine during its operation and maintenance. To acquire the service information of each general part under the environment of high temperature and serious oil pollution for predicting remaining life and preventative maintenance, a digital twin-driven monitoring and traceability system for general parts in continuous casting machine is proposed. First, the systematic architecture of proposed approach is given in detail, where a typical five-layer model for digital twin-driven monitoring and traceability is established. Second, the Web-based 3D visualization monitoring for continuous casting machine is achieved by using lightweight 3D twin model. After that, an assembly model based on polychromatic sets is built for expressing and describing the assembly relationships and assembly process of general parts. Meanwhile, an encoding rule for part and position is put forward by considering assembly position information. On the basis of that, the general parts with total process information are traced in the service life cycle. Finally, digital twin-based 3D visualization monitoring and traceability prototype system is developed and implemented, where the experiment cases verify the effectiveness and feasibility of the proposed approach.
Safety is an important requirement in rehabilitation assist suits. We have developed a velocity-based mechanical safety device (VBMSD) for an assist suit to aid in the flexion and extension of a patient’s knee joint. The VBMSD is attached to the assist suit. The VBMSD stops the suit’s motor when the angular velocity of the knee joint matches or exceeds a preset threshold level. This level is called the “detection velocity level (DVL)” and it is adjustable based on the specification of each patient’s gait training. Since the VBMSD is composed only of passive mechanical elements such as a rotary damper, it works even when the suit’s computer has stopped working. In view that portability is equally important as safety in wearable assist devices, the size and the weight of the VBMSD must be reduced for practical use. This paper presents the design and development of a new compact and light VBMSD. First, we describe the problems in the previous VBMSD. Second, we present the requirements and design specifications in the new VBMSD. The requirements and design specifications in the new VBMSD’s size are determined by considering International Organization for Standardization (ISO) 13482 and Advanced Industrial Science and Technology (AIST) human body dimensions data. Third, we propose the structure and the mechanism of the new VBMSD. Fourth, we explain the design process of the new VBMSD. In the design process, the frequency response and the transient response of the new VBMSD are also considered. Fifth, experimental results to check whether the new VBMSD achieves the necessary function are presented. Lastly, the possibility of installing the new VBMSD to an ankle joint assist suit and a wrist joint assist suit is discussed using AIST human body dimensions data, etc.
Based on the structural mechanics and rolling bearing dynamics, this paper presented a dynamics model of cylindrical roller bearing with flexible outer ring and a novel elastic support named groove elastic support(GES), and then the load distribution and cage slip ratio of cylindrical roller bearing with GES(BES) were analyzed. The findings are as following: (1) The number of loaded rollers of BES is more than that of cylindrical roller bearing with rigid support(BRS), and the largest contact load between roller and ring of BES is lower than that of BRS. (2) The number of loaded rollers of BES decreases with the groove number, arc beam thickness and outer ring’s thickness. The smaller radial load, ranging from 500N to 1400N in this paper, has no obvious effect on the number of loaded roller for BES and BRS; (3) Under the same condition, cage slip ratio of BES is much lower than that of BRS. Cage slip ratio of BES increases with the groove number, arc beam thickness and outer ring’s thickness. All results reveal that the GES has a large impact on the load distribution and cage slip ratio in cylindrical roller bearing, and will be beneficial to extend the bearing service life under the condition of high-speed and light-load.
Internal energy minimization has been used to select the two free parameters of the planar cubic Hermite curve. In this paper, we consider to combine the three well known internal energies and select the two free parameters of the planar cubic Hermite curve by minimizing the combined internal energy. The proposed minimization is a generalization of the single internal energy minimizations. Some numerical examples show that the proposed method can synchronously make the three internal energies of the curve as small as possible.
Time-frequency analysis can effectively reveal the fault characteristics of rolling bearings under variable speed conditions. However, the traditional time-frequency analysis method cannot meet the requirements of anti-noise ability and time-frequency concentration. The synchroextracting transform (SET) as a novel time-frequency analysis method makes up for these defects, so the envelope demodulation time-frequency analysis method based on SET for fault diagnosis is proposed. Firstly, the best resonant band is selected by the adaptive band-pass filter based on fast spectral kurtosis. Then, the amplitude envelope of filtered signal is calculated by the Hilbert transform. Finally, SET is applied to analyze the amplitude envelope, and the fault information can be extracted from the envelope demodulation spectrum. The simulation signal and experimental signal are analyzed respectively. The results prove the effectiveness of the method. Compared with the short-time Fourier transform (STFT) and synchrosqueezing transform (SST), the proposed method is more prominent in the anti-noise property and time-frequency concentration. In addition, the performance in case of the band-pass filter failure is tested. The results show that the proposed method is still valid, and has excellent robustness and self-adaptability. Therefore, the proposed method shows significant application prospects and promotion value for fault diagnosis of variable-speed rolling bearing.
In this paper, we present a new method for generating high-accuracy developable surface from two design curves via crow search algorithm (CSA) based modification of design curves. For achieving high-accuracy developability, we allow perturbation of the control points of design curves within a allowed bound to expand the solution space of developable surfaces, and search within the allowed perturbation bound for the set of optimal control points with which the resultant surface has the highest degree of developability via CSA. As a result, design curves are automatically and intelligently modified when that is necessary for achieving a high-accuracy developability. Modeling examples demonstrate that the method is effective and easy to implement to obtain high-accuracy developables.
In most motion control problems, precise settling in terminal time of control is a crucial specification. Totani and Nishimura, thus proposed the final-state control (FSC) technique which satisfies the required final-state conditions precisely. Then, the authors proposed a real-time updating version of FSC (updating final-state control: UFSC) by taking the application to time-varying final-state conditions into account. However, huge control inputs often occur at the final control time to suppress the error between the final-state conditions and real state variables, making it challenging to apply UFSC to practical problems. This paper proposes three improved control methods taking the input constraints at the final control time into account to improve feasibility. These are (i) frequency-shaping method (FSM), (ii) time-varying weighting method (TVWM), and (iii) input freezing method (IFM). The effectiveness of the methods has been discussed by comparing the numerical simulation results of a case study. The case study is a mid-air retrieval problem of low-speed-descent objects using fixed-wing unmanned aerial vehicles, which is also discussed in the authors’ prior study. The feasibility of the trajectory generated by the UFSC is also confirmed via experimental demonstration. As a result, this paper concludes the IFM based UFSC is the most realistic method for the control problem.
For the finger seal, the impact of structural parameters on its performance is complicated, and it is difficult and contradictory to lower its leakage and wear synchronously. Therefore, the problems relating to decision-making of optimal results and selection of reference variables still confuse the optimization of finger seal. In this paper, the performance (leakage and wear) of finger seal are calculated with finite element simulation, and a sensitivity analysis is carried out based on grey correlation method to obtain the influence degrees of structural parameters on the performance of finger seal; then a multi-objective optimization model is proposed by the combination of genetic algorithm, BP neural network and Nash equilibrium game theory; finally, the experiments of finger seals with various optimal structures are carried out to verify the theory and method established in this paper. The theoretical and experimental results indicate that the finger seal optimized with the model proposed in this paper has a better synthetical performance, which proves its feasibility. The theory and method established in this paper can be applied to enhance the synthetical performance of finger seals effectively.
Multi-tasking machine tools that can deal with several kinds of machining methods including turning and 5-axis control milling are attracted to achieve highly efficient machining in recent years. However, the machining process is generally complicated and the preparatory time becomes longer because there are a lot of available machining methods and the operational parameters such as the tool posture. Therefore, a computer aided process planning (CAPP) system is indispensable to reduce the efforts for the preparation and to improve the efficiency of machining process on multi-tasking machine tools. For this purpose, this study aims to propose a novel features recognition method can be applied to process planning of 5-axis index milling that is a characteristic machining method for mechanical parts having complex shapes on multi-tasking machine tools. In this method, machining primitives are obtained by dividing the removal volume, and cylindrical machining primitives for turning are additionally obtained even when the target shape does not have a cylinder part. Then, available combinations of tool postures are prepared for each machining primitive depending on the directions in which the machining primitive can be machined. The tool postures during 5-axis index milling are determined by referring specific information such as the number of tool postures. The machining primitives are divided again in each determined tool posture to recognize machining features in order to remove unmachined volume. Thus, the proposed method could be easily applied to process planning of 5-axis index milling on 5-axis controlled machining centers. The results of case study confirm that process planning of 5-axis index milling on multitasking machine tools is effectively realized based on the proposed method.
Conventional methods cannot accurately predict buildup rate. In this study, an algorithm was developed to predict the geometric deflection rate of the tool considering the influence of the radial displacement of a combined bearing. Three-point geometry was used to calculate the buildup rate and its relationship with the radial displacement of the combined bearing. The relation between the maximum spindle deflection and the load of the combined bearing was also determined by treating the spindle as a statically indeterminate beam. To consider the internal structural parameters of the combined bearing, a mathematical relationship was obtained between its load and radial displacement with the Stribeck maximum rolling element load formula and Palmgren roller bearing displacement formula. The influence of the structural parameters of the combined bearing on the buildup rate was analyzed, and the results showed that the buildup rate can be increased by increasing the thickness and pre-compression of the disc spring and decreasing its diameter ratio and the radial clearance of the self-aligning roller bearing. An experimental device was used to obtain test results with different maximum spindle deflection values. In particular, the error was less than 1% when the maximum spindle deflection was more than 4 mm.