Titanium alloy has been applied in the field of aerospace manufacturing for its high specific strength and hardness.Nonetheless,these properties also cause general problems in the machining,such as processing ineffici...Titanium alloy has been applied in the field of aerospace manufacturing for its high specific strength and hardness.Nonetheless,these properties also cause general problems in the machining,such as processing inefficiency,serious wear,poor workpiece face quality,etc.Aiming at the above problems,this paper carried out a comparative experimental study on titanium alloy milling based on the CAMCand BEMC.The variation law of cutting force and wear morphology of the two tools were obtained,and the wear mechanism and the effect of wear on machining quality were analyzed.The conclusion is that in contrast with BEMC,under the action of cutting thickness thinning mechanism,the force of CAMC was less,and its fluctuation was more stable.The flank wear was uniform and near the cutting edge,and the wear rate was slower.In the early period,the wear mechanism of CAMC was mainly adhesion.Gradually,oxidative wear also occurred with milling.Furthermore,the surface residual height of CAMC was lower.There is no obvious peak and trough accompanied by fewer surface defects.展开更多
The cutting force prediction is essential to optimize the process parameters of machining such as feed rate optimization, etc. Due to the significant influences of the runout effect on cutting force variation in milli...The cutting force prediction is essential to optimize the process parameters of machining such as feed rate optimization, etc. Due to the significant influences of the runout effect on cutting force variation in milling process, it is necessary to incorporate the cutter runout parameters into the prediction model of cutting forces. However, the determination of cutter runout parameters is still a challenge task until now. In this paper, cutting process geometry models, such as uncut chip thickness and pitch angle, are established based on the true trajectory of the cutting edge considering the cutter runout effect. A new algorithm is then presented to compute the cutter runout parameters for flat-end mill utilizing the sampled data of cutting forces and derived process geometry parameters. Further, three-axis and five-axis milling experiments were conducted on a machining centre, and resulting cutting forces were sampled by a three-component dynamometer. After computing the corresponding cutter runout parameters, cutter forces are simulated embracing the cutter runout parameters obtained from the proposed algorithm. The predicted cutting forces show good agreements with the sampled data both in magnitude and shape, which validates the feasibility and effectivity of the proposed new algorithm of determining cutter runout parameters and the new way to accurately predict cutting forces. The proposed method for computing the cutter runout parameters provides the significant references for the cutting force prediction in the cutting process.展开更多
Form milling cutter is built-for-purpose cutter which process the form surface, for example, usually process male and female circular arc face and form trench and so on. From the traditional concept, form milling cutt...Form milling cutter is built-for-purpose cutter which process the form surface, for example, usually process male and female circular arc face and form trench and so on. From the traditional concept, form milling cutter is divided into pointed tooth and relieving follow its structure. Relieving shaped cutter is more convenient than pointed tooth milling cutter, because only its rake face is needed to grind after it turn into blunting, so the current books which are used in college almost select relieving shaped cutter in order to introduce how to design the form milling cutter.The curve of the back of tooth of relieving cutter is the transversal which is formed by the rear face of tooth in the end cut plane of the milling cutter. In the past, because of the limit of the manufacturing technology, the curve of the back of tooth is often selected Archimedes’ curve, in order that the shovel-nose tool acquire the uniform motion when the cutter shovel the back, in other word, the rear face of the milling cutter rotate its axis by the new cutting lip, in the same time, it move uniformly to the axis in order to form the surface. Although this curve of the back of tooth meet the fixedness of the form of blade around grinding the cutter, the rear angle of the dot of the cutting lip don’t keep fixedness. With the development of the modern manufacturing technology, the unmanageable problem of many complex curves is already easily solved. So it is need to study the optimum profile of the curve of the back of tooth in theory, and study the design theory of the relieving shaped cutter under the condition of new manufacture, in order to ensure that the rear angle of the dot of the cutting lip keep fixedness after the relieving shaped cutter is grinded. The paper derive the curve profile of tooth of the form cutter and the modifier calculation formula of the profile of the cutter edge from the definition of the rear angle of the cutter, which establish the foundation for the precision design and manufacture of other form cutter.展开更多
When machining D60 steel by high speed turn-milling under the different cooling and lubricating conditions, the cutting performance and the wear mechanism of the cermet cutter are researched. With water soluble coolin...When machining D60 steel by high speed turn-milling under the different cooling and lubricating conditions, the cutting performance and the wear mechanism of the cermet cutter are researched. With water soluble cooling fluid, the wear performance of the cermet cutter is bad, and does not adapt to the requirements of machining. However, when machining D60 by high speed turn-milling is under dry conditions, the wearing performance of the cermet cutter is very good and the cutting time lasts almost 3 hours. The wear mechanism of the cermet cutter under the water soluble cooling fluid is different from the dry condition. With the water soluble cooling fluid, a great deal of little chap units are formed since high frequency alternates heat stress. The crash and desquamate of these chap units is the main cause of the cutter wearing. Under dry cutting conditions, it is the main cause of cermet cutter wear in the felting phase intenerating causing rigid phase grains to fall.展开更多
How to generate rake faces of nonconventional milling cutters (NCMC) with constant spiral angled and normal rake angled edges on NC machine tools is presented by use of a blunt cup grinder or a cup milling cutter. Mot...How to generate rake faces of nonconventional milling cutters (NCMC) with constant spiral angled and normal rake angled edges on NC machine tools is presented by use of a blunt cup grinder or a cup milling cutter. Motion functions of the NC machining system are mathematically deduced and exam- ed by a experiment. The research will provide theoretical and practical guidance for machining noncon- ventional tools on NC machine tools.展开更多
Taking the minimum chip thickness effect,cutter deflection,and spindle run-out into account,a micro milling force model and a method to determine the optimal micro milling parameters were developed.The micro milling f...Taking the minimum chip thickness effect,cutter deflection,and spindle run-out into account,a micro milling force model and a method to determine the optimal micro milling parameters were developed.The micro milling force model was derived as a function of the cutting coefficients and the instantaneous projected cutting area that was determined based on the machining parameters and the rotation trajectory of the cutter edges.When an allowable micro cutter deflection is defined,the maximum allowable cutting force can be determined.The optimal machining parameters can then be computed based on the cutting force model for better machining efficiency and accuracy.To verify the proposed cutting force model and the method to determine the optimal cutting parameters,micro-milling experiments were conducted,and the results show the feasibility and effectiveness of the model and method.展开更多
Geometry of end mill cutters plays a vital role in the stability of the flexible parts milling.The present study considers helix angle and number of flutes.Multi-frequency solution is established to draw stability Lob...Geometry of end mill cutters plays a vital role in the stability of the flexible parts milling.The present study considers helix angle and number of flutes.Multi-frequency solution is established to draw stability Lobe diagram(SLD)for different helix angles and number of flutes.SLD for the two cases shows that the greater the value of helix angle,the more stable the milling process will be,and conversely increasing the number of flutes degrades the stability of flexible parts milling.A simple empirical methodology is adopted to employ the inclined plane workpiece geometry offering agradual increase of the axial depth of cut in the feed direction.Surface roughness is used as a measure of stability.Test results corroborate the model conclusions very well.展开更多
Five-axis ball-end milling is commonly used to machine the complex surfaces. Local tool interference phenomenon which often occurs in five-axis milling should be urgently solved. In this paper, a simplified method to ...Five-axis ball-end milling is commonly used to machine the complex surfaces. Local tool interference phenomenon which often occurs in five-axis milling should be urgently solved. In this paper, a simplified method to detect the occurrence of local tool interference and modify tool position is proposed. First, the detection matrix is established to detect local tool interference at all the cutter location points on tool path simultaneously in five-axis ball-end milling of complex surfaces. The algorithm of detection matrix based on point arithmetic is simple. Secondly, the new coordinates of the modified interfering-free points are obtained precisely by using the genetic algorithm. The feasibility of the method is validated by simulation in Matlab. This research is benefit to simplify the calculation of local tool interference detection and tool position modification.展开更多
Turn-milling which history dates from the end of the 20th century is one of the advanced metal cutting technologies. It could precisely machine hard materials as an alternative to turning for certain limitations. A se...Turn-milling which history dates from the end of the 20th century is one of the advanced metal cutting technologies. It could precisely machine hard materials as an alternative to turning for certain limitations. A series of orthogonal turn-milling surface veins experiments have been done on the turn-milling machining center by machining aluminum alloy,and then the nexus between the surface veins and the cutting regimes is studied. The mathematical model for surface vein direction angle is established,also the forming mechanics of surface vein direction is analyzed. Its variety regulation presents decreasing trend with as axial feed and cutter rotary speed increasing. For different eccentric distance of orthogonal turn-milling,the surface veins are different.展开更多
针对铣刀磨损量预测时精度低的问题,提出一种基于黑寡妇算法(BWO)优化的长短期记忆神经网络(LSTM)与AdaBoost集成学习算法相结合的铣刀磨损量预测方法。在铣刀磨损振动信号中提取时域、频域以及时频域多域特征。通过BWO算法优化LSTM的...针对铣刀磨损量预测时精度低的问题,提出一种基于黑寡妇算法(BWO)优化的长短期记忆神经网络(LSTM)与AdaBoost集成学习算法相结合的铣刀磨损量预测方法。在铣刀磨损振动信号中提取时域、频域以及时频域多域特征。通过BWO算法优化LSTM的核心参数,并将优化后的LSTM网络与AdaBoost算法进行结合,构建铣刀磨损量预测模型。最后用PHM Society 2010铣刀全寿命周期的振动数据进行实验。研究结果表明:所提方法能够有效地预测出铣刀磨损量变化值,优化后模型的平均绝对误差百分比为3.436%、均方根误差为6.471、决定系数R^(2)为0.935。该方法能够获得准确率更高的铣刀磨损量预测值,预测效率更高。展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51975168).
文摘Titanium alloy has been applied in the field of aerospace manufacturing for its high specific strength and hardness.Nonetheless,these properties also cause general problems in the machining,such as processing inefficiency,serious wear,poor workpiece face quality,etc.Aiming at the above problems,this paper carried out a comparative experimental study on titanium alloy milling based on the CAMCand BEMC.The variation law of cutting force and wear morphology of the two tools were obtained,and the wear mechanism and the effect of wear on machining quality were analyzed.The conclusion is that in contrast with BEMC,under the action of cutting thickness thinning mechanism,the force of CAMC was less,and its fluctuation was more stable.The flank wear was uniform and near the cutting edge,and the wear rate was slower.In the early period,the wear mechanism of CAMC was mainly adhesion.Gradually,oxidative wear also occurred with milling.Furthermore,the surface residual height of CAMC was lower.There is no obvious peak and trough accompanied by fewer surface defects.
基金supported by National Natural Science Foundation of China (Grant No. 51075054)National Basic Research Program of China (973 Program, Grant No. 2005CB724100)Program for New Century Excellent Talents in University of China (Grant No. NCET-08-081)
文摘The cutting force prediction is essential to optimize the process parameters of machining such as feed rate optimization, etc. Due to the significant influences of the runout effect on cutting force variation in milling process, it is necessary to incorporate the cutter runout parameters into the prediction model of cutting forces. However, the determination of cutter runout parameters is still a challenge task until now. In this paper, cutting process geometry models, such as uncut chip thickness and pitch angle, are established based on the true trajectory of the cutting edge considering the cutter runout effect. A new algorithm is then presented to compute the cutter runout parameters for flat-end mill utilizing the sampled data of cutting forces and derived process geometry parameters. Further, three-axis and five-axis milling experiments were conducted on a machining centre, and resulting cutting forces were sampled by a three-component dynamometer. After computing the corresponding cutter runout parameters, cutter forces are simulated embracing the cutter runout parameters obtained from the proposed algorithm. The predicted cutting forces show good agreements with the sampled data both in magnitude and shape, which validates the feasibility and effectivity of the proposed new algorithm of determining cutter runout parameters and the new way to accurately predict cutting forces. The proposed method for computing the cutter runout parameters provides the significant references for the cutting force prediction in the cutting process.
文摘Form milling cutter is built-for-purpose cutter which process the form surface, for example, usually process male and female circular arc face and form trench and so on. From the traditional concept, form milling cutter is divided into pointed tooth and relieving follow its structure. Relieving shaped cutter is more convenient than pointed tooth milling cutter, because only its rake face is needed to grind after it turn into blunting, so the current books which are used in college almost select relieving shaped cutter in order to introduce how to design the form milling cutter.The curve of the back of tooth of relieving cutter is the transversal which is formed by the rear face of tooth in the end cut plane of the milling cutter. In the past, because of the limit of the manufacturing technology, the curve of the back of tooth is often selected Archimedes’ curve, in order that the shovel-nose tool acquire the uniform motion when the cutter shovel the back, in other word, the rear face of the milling cutter rotate its axis by the new cutting lip, in the same time, it move uniformly to the axis in order to form the surface. Although this curve of the back of tooth meet the fixedness of the form of blade around grinding the cutter, the rear angle of the dot of the cutting lip don’t keep fixedness. With the development of the modern manufacturing technology, the unmanageable problem of many complex curves is already easily solved. So it is need to study the optimum profile of the curve of the back of tooth in theory, and study the design theory of the relieving shaped cutter under the condition of new manufacture, in order to ensure that the rear angle of the dot of the cutting lip keep fixedness after the relieving shaped cutter is grinded. The paper derive the curve profile of tooth of the form cutter and the modifier calculation formula of the profile of the cutter edge from the definition of the rear angle of the cutter, which establish the foundation for the precision design and manufacture of other form cutter.
文摘When machining D60 steel by high speed turn-milling under the different cooling and lubricating conditions, the cutting performance and the wear mechanism of the cermet cutter are researched. With water soluble cooling fluid, the wear performance of the cermet cutter is bad, and does not adapt to the requirements of machining. However, when machining D60 by high speed turn-milling is under dry conditions, the wearing performance of the cermet cutter is very good and the cutting time lasts almost 3 hours. The wear mechanism of the cermet cutter under the water soluble cooling fluid is different from the dry condition. With the water soluble cooling fluid, a great deal of little chap units are formed since high frequency alternates heat stress. The crash and desquamate of these chap units is the main cause of the cutter wearing. Under dry cutting conditions, it is the main cause of cermet cutter wear in the felting phase intenerating causing rigid phase grains to fall.
文摘How to generate rake faces of nonconventional milling cutters (NCMC) with constant spiral angled and normal rake angled edges on NC machine tools is presented by use of a blunt cup grinder or a cup milling cutter. Motion functions of the NC machining system are mathematically deduced and exam- ed by a experiment. The research will provide theoretical and practical guidance for machining noncon- ventional tools on NC machine tools.
基金Project(NSC98-2221-E-033-047)supported by National Science Council
文摘Taking the minimum chip thickness effect,cutter deflection,and spindle run-out into account,a micro milling force model and a method to determine the optimal micro milling parameters were developed.The micro milling force model was derived as a function of the cutting coefficients and the instantaneous projected cutting area that was determined based on the machining parameters and the rotation trajectory of the cutter edges.When an allowable micro cutter deflection is defined,the maximum allowable cutting force can be determined.The optimal machining parameters can then be computed based on the cutting force model for better machining efficiency and accuracy.To verify the proposed cutting force model and the method to determine the optimal cutting parameters,micro-milling experiments were conducted,and the results show the feasibility and effectiveness of the model and method.
文摘Geometry of end mill cutters plays a vital role in the stability of the flexible parts milling.The present study considers helix angle and number of flutes.Multi-frequency solution is established to draw stability Lobe diagram(SLD)for different helix angles and number of flutes.SLD for the two cases shows that the greater the value of helix angle,the more stable the milling process will be,and conversely increasing the number of flutes degrades the stability of flexible parts milling.A simple empirical methodology is adopted to employ the inclined plane workpiece geometry offering agradual increase of the axial depth of cut in the feed direction.Surface roughness is used as a measure of stability.Test results corroborate the model conclusions very well.
基金Funded by the National Natural Science Foundation of China (No.51575321)the Major Science and Technology Innovation Project of Shandong Province (No.2018CXGC0804)Taishan Scholars Program of Shandong Province (No.ts201712002)
文摘Five-axis ball-end milling is commonly used to machine the complex surfaces. Local tool interference phenomenon which often occurs in five-axis milling should be urgently solved. In this paper, a simplified method to detect the occurrence of local tool interference and modify tool position is proposed. First, the detection matrix is established to detect local tool interference at all the cutter location points on tool path simultaneously in five-axis ball-end milling of complex surfaces. The algorithm of detection matrix based on point arithmetic is simple. Secondly, the new coordinates of the modified interfering-free points are obtained precisely by using the genetic algorithm. The feasibility of the method is validated by simulation in Matlab. This research is benefit to simplify the calculation of local tool interference detection and tool position modification.
基金Sponsored by Doctoral Science Foundation of Shenyang Ligong University (BS04007)
文摘Turn-milling which history dates from the end of the 20th century is one of the advanced metal cutting technologies. It could precisely machine hard materials as an alternative to turning for certain limitations. A series of orthogonal turn-milling surface veins experiments have been done on the turn-milling machining center by machining aluminum alloy,and then the nexus between the surface veins and the cutting regimes is studied. The mathematical model for surface vein direction angle is established,also the forming mechanics of surface vein direction is analyzed. Its variety regulation presents decreasing trend with as axial feed and cutter rotary speed increasing. For different eccentric distance of orthogonal turn-milling,the surface veins are different.
文摘针对铣刀磨损量预测时精度低的问题,提出一种基于黑寡妇算法(BWO)优化的长短期记忆神经网络(LSTM)与AdaBoost集成学习算法相结合的铣刀磨损量预测方法。在铣刀磨损振动信号中提取时域、频域以及时频域多域特征。通过BWO算法优化LSTM的核心参数,并将优化后的LSTM网络与AdaBoost算法进行结合,构建铣刀磨损量预测模型。最后用PHM Society 2010铣刀全寿命周期的振动数据进行实验。研究结果表明:所提方法能够有效地预测出铣刀磨损量变化值,优化后模型的平均绝对误差百分比为3.436%、均方根误差为6.471、决定系数R^(2)为0.935。该方法能够获得准确率更高的铣刀磨损量预测值,预测效率更高。
