The worm wheel whose undercutting characteristic is researched is a member of offsetting normal arc-toothed cylindrical worm drive.The tooth profile of the worm in its offsetting normal section is a circular arc.The n...The worm wheel whose undercutting characteristic is researched is a member of offsetting normal arc-toothed cylindrical worm drive.The tooth profile of the worm in its offsetting normal section is a circular arc.The normal vector used to calculate the first-type limit function is determined in the natural frame without the aid of the curvature parameter of worm helicoid.The first-type limit line is ascertained via solving the nonlinear equations iteratively.It is discovered that one first-type limit line exists on the tooth surface of worm wheel by numerical simulation,and such a line is normally located out of the meshing zone.Only one intersection point exists between the first and second-types of limit lines,and this point is a lubrication weak point.The undercutting mechanism is essentially that a part of the meshing zone near the conjugated line of worm tooth crest will come into the undercutting area and will be cut off during machining the worm wheel.The machining simulation verifies the correctness of undercutting mechanism.Moreover,a convenient and practical characteristic quantity is proposed to judge whether the undercutting exists in the whole meshing zone via computing the first-type limit function values on the worm tooth crest.展开更多
Worm grinding has been applied to manufacture gears to pursue high accuracy and fine surface finish.When the worm used to grind face gears is manufactured with multi-axis computer numerical control(CNC)machining,the m...Worm grinding has been applied to manufacture gears to pursue high accuracy and fine surface finish.When the worm used to grind face gears is manufactured with multi-axis computer numerical control(CNC)machining,the machining accuracy is usually improved by increasing the number of tool paths with more time cost.Differently,this work proposes a generated method to improve the efficiency by dressing the worm surface with only one path,and a closed-loop manufacturing process is applied to ensure the machining accuracy.According to an advanced geometric analysis,the worm surface is practically approximated as a swept surface generated by a planar curve.Meanwhile,this curve is applied as the profile of a dressing wheel,which is used to dress the worm surface.The practical machining is carried out in a CNC machine tool,which was originally used to grind helical gears.Finally,a closed-loop manufacturing process including machining,measurement,and modification is proposed to compensate the machining errors.The proposed method is validated with simulations and practical experiments.展开更多
The gradual hybrid anti-worm （GHAW） was presented. percentage of vulnerable hosts present in the network. For GHAW It changed its confrontation scheme in real time according to the its process of countering maliciou...The gradual hybrid anti-worm （GHAW） was presented. percentage of vulnerable hosts present in the network. For GHAW It changed its confrontation scheme in real time according to the its process of countering malicious internet worms was modeled. The performance of GHAW on two factors was also estimated： confronting validity against worms and consumption of network resources. Factors governing its performance, specifically the transformation threshold and the transformation rate, were analyzed. The simulation experiments show that GHAW has dynamical adaptability to changes of network conditions and offers the same level of effectiveness on confronting internet worms as the divide-and-rule hybrid anti-worm, with significantly less cost to network resources. The experiments also indicate that the transformation threshold is the key factor affecting the performance of GHAW.展开更多
In order to take precaution and cure against intemet of vehicles （IOV） worm propagation in expressway, the IOV worm propagation and its corresponding anti-worm strategy were studied in expressway interchange termina...In order to take precaution and cure against intemet of vehicles （IOV） worm propagation in expressway, the IOV worm propagation and its corresponding anti-worm strategy were studied in expressway interchange terminal. According to omnirange driving in expressway interchange terminal and vehicular mobile communication environment, an IOV worm propagation model is constructed; and then according to the dynamic propagation law and destructiveness of IOV worm in this environment, a novel hybrid anti-worm strategy for confrontation is designed. This worm propagation model can factually simulates the IOV worm propagation in this interchange terminal environment; and this hybrid anti-worm strategy can effectively control IOV worm propagation in the environment, moreover, it can reduce the influence on network resource overhead.展开更多
Aiming at the issue of the grinding integrity of face-gear with worm wheel, the envelope mathematical model of shaper, worm wheel and face-gear is established based on theories of differential geometry and gear mesh. ...Aiming at the issue of the grinding integrity of face-gear with worm wheel, the envelope mathematical model of shaper, worm wheel and face-gear is established based on theories of differential geometry and gear mesh. The judgment of completely grinding the face-gear with the avoidance of singularities is established, and the mathematical expression to show the reason why singularities appear is derived, through the research on the surface contact area and singularity rules of the worm thread surface. The disadvantage of current face-gear grinding method that only part of the working surface of the face-gear can be covered is analyzed and the influence of coefficient of judgment is studied through changing the design parameters.展开更多
The machining principle and realization method for the continuous generative grinding face gear by a worm wheel are introduced. Based on a five-axis linked CNC grinding machine, a new method is presented to deprive th...The machining principle and realization method for the continuous generative grinding face gear by a worm wheel are introduced. Based on a five-axis linked CNC grinding machine, a new method is presented to deprive the equation of face gear error tooth surface by assuming the tool surface as the error surface, where actual tool installation position error is introduced into the equation of virtual shaper cutter. Surface equations and 3-D models for the face gear and the worm wheel involving four kinds of tool installation errors are established. When compared, the face gear tooth surface machined in VERICUT software for simulation based on this new method and the one obtained based on real process(grinding face gear by using a theoretical worm wheel with actual position errors) are found to be coincident, which proves the validity and feasibility of this new method. By using mesh planning for the rotating projection plane of the face gear work tooth surface, the deviation values of the tooth surface and the difference surface are acquired, and the influence of four kinds of errors on the face gear tooth surface is analyzed. Accordingly, this work provides a theoretical reference for assembly craft of worm wheel, improvement of face gear machining accuracy and modification of error tooth surface.展开更多
A new multi-modal optimization algorithm called the self-organizing worm algorithm （SOWA） is presented for optimization of multi-modal functions. The main idea of this algorithm can be described as follows： dispers...A new multi-modal optimization algorithm called the self-organizing worm algorithm （SOWA） is presented for optimization of multi-modal functions. The main idea of this algorithm can be described as follows： disperse some worms equably in the domain; the worms exchange the information each other and creep toward the nearest high point; at last they will stop on the nearest high point. All peaks of multi-modal function can be found rapidly through studying and chasing among the worms. In contrast with the classical multi-modal optimization algorithms, SOWA is provided with a simple calculation, strong convergence, high precision, and does not need any prior knowledge. Several simulation experiments for SOWA are performed, and the complexity of SOWA is analyzed amply. The results show that SOWA is very effective in optimization of multi-modal functions.展开更多
The gears of new energy vehicles are required to withstand higher rotational speeds and greater loads,which puts forward higher precision essentials for gear manufacturing.However,machining process parameters can caus...The gears of new energy vehicles are required to withstand higher rotational speeds and greater loads,which puts forward higher precision essentials for gear manufacturing.However,machining process parameters can cause changes in cutting force/heat,resulting in affecting gear machining precision.Therefore,this paper studies the effect of different process parameters on gear machining precision.A multi-objective optimization model is established for the relationship between process parameters and tooth surface deviations,tooth profile deviations,and tooth lead deviations through the cutting speed,feed rate,and cutting depth of the worm wheel gear grinding machine.The response surface method(RSM)is used for experimental design,and the corresponding experimental results and optimal process parameters are obtained.Subsequently,gray relational analysis-principal component analysis(GRA-PCA),particle swarm optimization(PSO),and genetic algorithm-particle swarm optimization(GA-PSO)methods are used to analyze the experimental results and obtain different optimal process parameters.The results show that optimal process parameters obtained by the GRA-PCA,PSO,and GA-PSO methods improve the gear machining precision.Moreover,the gear machining precision obtained by GA-PSO is superior to other methods.展开更多
基金Projects(52205069,52075083,52304049)supported by the National Natural Science Foundation of ChinaProject(2021-BS-164)supported by the Liaoning Province Doctoral Research Startup Fund,China+2 种基金Project(LJKZ0264)supported by the Science and Technology Research Projects of Education Department of Liaoning Province,ChinaProject(G2022003010L)supported by the High-end Foreign Experts Recruitment Plan of ChinaProject(E2021203095)supported by the Natural Science Foundation for Young Scholars of Hebei Province,China。
文摘The worm wheel whose undercutting characteristic is researched is a member of offsetting normal arc-toothed cylindrical worm drive.The tooth profile of the worm in its offsetting normal section is a circular arc.The normal vector used to calculate the first-type limit function is determined in the natural frame without the aid of the curvature parameter of worm helicoid.The first-type limit line is ascertained via solving the nonlinear equations iteratively.It is discovered that one first-type limit line exists on the tooth surface of worm wheel by numerical simulation,and such a line is normally located out of the meshing zone.Only one intersection point exists between the first and second-types of limit lines,and this point is a lubrication weak point.The undercutting mechanism is essentially that a part of the meshing zone near the conjugated line of worm tooth crest will come into the undercutting area and will be cut off during machining the worm wheel.The machining simulation verifies the correctness of undercutting mechanism.Moreover,a convenient and practical characteristic quantity is proposed to judge whether the undercutting exists in the whole meshing zone via computing the first-type limit function values on the worm tooth crest.
基金Project(2019 YFB 2004700)supported by the National Key R&D Project of ChinaProject(HTL-O-19 K 02)supported by National Key Laboratory of Science and Technology on Helicopter Transmission,Nanjing University of Aeronautics and Astronautics,China。
文摘Worm grinding has been applied to manufacture gears to pursue high accuracy and fine surface finish.When the worm used to grind face gears is manufactured with multi-axis computer numerical control(CNC)machining,the machining accuracy is usually improved by increasing the number of tool paths with more time cost.Differently,this work proposes a generated method to improve the efficiency by dressing the worm surface with only one path,and a closed-loop manufacturing process is applied to ensure the machining accuracy.According to an advanced geometric analysis,the worm surface is practically approximated as a swept surface generated by a planar curve.Meanwhile,this curve is applied as the profile of a dressing wheel,which is used to dress the worm surface.The practical machining is carried out in a CNC machine tool,which was originally used to grind helical gears.Finally,a closed-loop manufacturing process including machining,measurement,and modification is proposed to compensate the machining errors.The proposed method is validated with simulations and practical experiments.
基金Project(61070194) supported by the National Natural Science Foundation of ChinaProject([2009]1886) supported by the Information Security Industrialization Fund from NDRC of China in 2009+1 种基金Project(CJ[2010]341) supported by the Major Achievements Transfer Projects of MOF and MIIT of China in 2010Project(2011FJ2003) supported by the Natural Science Foundation of Hunan Province, China
文摘The gradual hybrid anti-worm （GHAW） was presented. percentage of vulnerable hosts present in the network. For GHAW It changed its confrontation scheme in real time according to the its process of countering malicious internet worms was modeled. The performance of GHAW on two factors was also estimated： confronting validity against worms and consumption of network resources. Factors governing its performance, specifically the transformation threshold and the transformation rate, were analyzed. The simulation experiments show that GHAW has dynamical adaptability to changes of network conditions and offers the same level of effectiveness on confronting internet worms as the divide-and-rule hybrid anti-worm, with significantly less cost to network resources. The experiments also indicate that the transformation threshold is the key factor affecting the performance of GHAW.
基金Project(61005008) supported by the National Natural Science Foundation of ChinaProject(JI300D004) supported by the COSTIND Application Foundation of China
文摘In order to take precaution and cure against intemet of vehicles （IOV） worm propagation in expressway, the IOV worm propagation and its corresponding anti-worm strategy were studied in expressway interchange terminal. According to omnirange driving in expressway interchange terminal and vehicular mobile communication environment, an IOV worm propagation model is constructed; and then according to the dynamic propagation law and destructiveness of IOV worm in this environment, a novel hybrid anti-worm strategy for confrontation is designed. This worm propagation model can factually simulates the IOV worm propagation in this interchange terminal environment; and this hybrid anti-worm strategy can effectively control IOV worm propagation in the environment, moreover, it can reduce the influence on network resource overhead.
基金Projects(51275530,51535012) supported by the National Natural Science Foundation of ChinaProject(2011CB706800) supported by the National Basic Research Program of China
文摘Aiming at the issue of the grinding integrity of face-gear with worm wheel, the envelope mathematical model of shaper, worm wheel and face-gear is established based on theories of differential geometry and gear mesh. The judgment of completely grinding the face-gear with the avoidance of singularities is established, and the mathematical expression to show the reason why singularities appear is derived, through the research on the surface contact area and singularity rules of the worm thread surface. The disadvantage of current face-gear grinding method that only part of the working surface of the face-gear can be covered is analyzed and the influence of coefficient of judgment is studied through changing the design parameters.
基金Projects(51535012,U1604255)supported by the National Natural Science Foundation of ChinaProject(2016JC2001)supported by the Key Research and Development Project of Hunan Province,China
文摘The machining principle and realization method for the continuous generative grinding face gear by a worm wheel are introduced. Based on a five-axis linked CNC grinding machine, a new method is presented to deprive the equation of face gear error tooth surface by assuming the tool surface as the error surface, where actual tool installation position error is introduced into the equation of virtual shaper cutter. Surface equations and 3-D models for the face gear and the worm wheel involving four kinds of tool installation errors are established. When compared, the face gear tooth surface machined in VERICUT software for simulation based on this new method and the one obtained based on real process(grinding face gear by using a theoretical worm wheel with actual position errors) are found to be coincident, which proves the validity and feasibility of this new method. By using mesh planning for the rotating projection plane of the face gear work tooth surface, the deviation values of the tooth surface and the difference surface are acquired, and the influence of four kinds of errors on the face gear tooth surface is analyzed. Accordingly, this work provides a theoretical reference for assembly craft of worm wheel, improvement of face gear machining accuracy and modification of error tooth surface.
基金the National Natural Science Foundation of China (70572045).
文摘A new multi-modal optimization algorithm called the self-organizing worm algorithm （SOWA） is presented for optimization of multi-modal functions. The main idea of this algorithm can be described as follows： disperse some worms equably in the domain; the worms exchange the information each other and creep toward the nearest high point; at last they will stop on the nearest high point. All peaks of multi-modal function can be found rapidly through studying and chasing among the worms. In contrast with the classical multi-modal optimization algorithms, SOWA is provided with a simple calculation, strong convergence, high precision, and does not need any prior knowledge. Several simulation experiments for SOWA are performed, and the complexity of SOWA is analyzed amply. The results show that SOWA is very effective in optimization of multi-modal functions.
基金Projects(U22B2084,52275483,52075142)supported by the National Natural Science Foundation of ChinaProject(2023ZY01050)supported by the Ministry of Industry and Information Technology High Quality Development,China。
文摘The gears of new energy vehicles are required to withstand higher rotational speeds and greater loads,which puts forward higher precision essentials for gear manufacturing.However,machining process parameters can cause changes in cutting force/heat,resulting in affecting gear machining precision.Therefore,this paper studies the effect of different process parameters on gear machining precision.A multi-objective optimization model is established for the relationship between process parameters and tooth surface deviations,tooth profile deviations,and tooth lead deviations through the cutting speed,feed rate,and cutting depth of the worm wheel gear grinding machine.The response surface method(RSM)is used for experimental design,and the corresponding experimental results and optimal process parameters are obtained.Subsequently,gray relational analysis-principal component analysis(GRA-PCA),particle swarm optimization(PSO),and genetic algorithm-particle swarm optimization(GA-PSO)methods are used to analyze the experimental results and obtain different optimal process parameters.The results show that optimal process parameters obtained by the GRA-PCA,PSO,and GA-PSO methods improve the gear machining precision.Moreover,the gear machining precision obtained by GA-PSO is superior to other methods.
