为了解决采集图像时相机与旋转铣刀刀刃位置不确定的问题及提高图像处理的时效性,提出了一种基于机器视觉的铣刀磨损在机检测方法。根据结构相似性算法判断刀具图像质量,并引入图像采集间隔角度系数,确定了图像采集间隔角度与主轴转速...为了解决采集图像时相机与旋转铣刀刀刃位置不确定的问题及提高图像处理的时效性,提出了一种基于机器视觉的铣刀磨损在机检测方法。根据结构相似性算法判断刀具图像质量,并引入图像采集间隔角度系数,确定了图像采集间隔角度与主轴转速。采用加速段特征测试(Features from accelerated segment test,FAST)算法实现了对刀具磨损区域快速、准确地自适应裁剪。基于FAST特征点提出了自适应阈值分割方法,有效提取出磨损区域边缘。采用Hough变换和最小外接矩形法,实现了对主切削刃倾斜角度的校正,进而提取出磨损区域B区的平均宽度。最后开展了铣削试验,在16组试验中,计算值与真实值的最大、最小和平均误差分别为4.76%、0.91%、3.63%。试验结果表明,该方法可在主轴旋转时获取所有铣刀磨损区域的高质量图像,进而高效、准确地提取磨损参数。展开更多
Though the lengthened shrink-fit holder (LSFH) is widely applied in high speed milling of the parts characterized by deep cavities at present, its design and selection mainly depends on the experience and lacks a corr...Though the lengthened shrink-fit holder (LSFH) is widely applied in high speed milling of the parts characterized by deep cavities at present, its design and selection mainly depends on the experience and lacks a correct theoretical guidance. In this paper, attention is focus on the radial grip rigidity of the matching of LSFH and cutter in high speed milling. Based on the experiment modal analysis (EMA) technique, an accurate finite element model of the matching of LSFH and cutter is established firstly. Subsequently, the influence of different interference, grip length and spindle speed on the grip rigidity of LSFH are analyzed. The analysis results show that there is a reasonable interference and grip length between the LSFH and cutter so that to have a steepless grip and have a good radial grip rigidity and at the same time to avoid the strength of LSFH to exceed it’s yield limit which will reduce the precision and service life of LSFH, besides when spindle speed reach a extension the weakening influence of the centrifugal force on the radial grip rigidity of the matching of LSFH and cutter should been taken into account. Finally, the finite element analysis results are verified based on the construction of measurement method of the grip rigidity and the results fit very well. The studies provide a theoretical basis for the design, selection and the serialization and standardization of the matching of LSFH and cutter.展开更多
Microstructural functional surfaces play an important role in energy conversion applications including power generation,air conditioning,and thermal management of electronics through the boiling process.In this study,...Microstructural functional surfaces play an important role in energy conversion applications including power generation,air conditioning,and thermal management of electronics through the boiling process.In this study,multi-scale microgroove surfaces were fabricated by the combination of wire electrical discharge machining(WEDM)and electrical discharge shaped machining(EDSM)to achieve a better boiling performance.The WEDM,with the advantage of high efficiency,was used to fabricate the first microgroove array,and rougher surfaces were formed by intense discharge.A wavy electrode was used in EDSM to fabricate the second microgroove array.Reentrant cavities at the intersections of microgrooves and rougher micro fins with spacing distribution were formed after EDSM.The boiling performance of the multi-scale microgroove surface was studied with water as the working medium under atmospheric pressure.The results indicated that the boiling performance of the microgroove surface is significantly enhanced.The critical heat flux and maximum heat transfer coefficient of microgroove surface were higher than the surfaces fabricated only by WEDM or EDSM,which were 2.34 and 3.29 times that of smooth copper plate,respectively.This study demonstrated that the combination of WEDM and EDSM is a convenient and effective method to fabricate high-performance microgroove boiling surfaces.展开更多
文摘为了解决采集图像时相机与旋转铣刀刀刃位置不确定的问题及提高图像处理的时效性,提出了一种基于机器视觉的铣刀磨损在机检测方法。根据结构相似性算法判断刀具图像质量,并引入图像采集间隔角度系数,确定了图像采集间隔角度与主轴转速。采用加速段特征测试(Features from accelerated segment test,FAST)算法实现了对刀具磨损区域快速、准确地自适应裁剪。基于FAST特征点提出了自适应阈值分割方法,有效提取出磨损区域边缘。采用Hough变换和最小外接矩形法,实现了对主切削刃倾斜角度的校正,进而提取出磨损区域B区的平均宽度。最后开展了铣削试验,在16组试验中,计算值与真实值的最大、最小和平均误差分别为4.76%、0.91%、3.63%。试验结果表明,该方法可在主轴旋转时获取所有铣刀磨损区域的高质量图像,进而高效、准确地提取磨损参数。
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2009AA44302)Scientific Research Fund of Hunan Provincial Education Department, China (Grant No. 10C1259)+2 种基金Hunan Provincial Planned Science and Technology Project of China (Grant No. 2011FJ3231)National Natural Science Foundation of China (Grant No. 51005194)Open Innovation Platform of Hunan College Fund, China (Grant No. 10K063)
文摘Though the lengthened shrink-fit holder (LSFH) is widely applied in high speed milling of the parts characterized by deep cavities at present, its design and selection mainly depends on the experience and lacks a correct theoretical guidance. In this paper, attention is focus on the radial grip rigidity of the matching of LSFH and cutter in high speed milling. Based on the experiment modal analysis (EMA) technique, an accurate finite element model of the matching of LSFH and cutter is established firstly. Subsequently, the influence of different interference, grip length and spindle speed on the grip rigidity of LSFH are analyzed. The analysis results show that there is a reasonable interference and grip length between the LSFH and cutter so that to have a steepless grip and have a good radial grip rigidity and at the same time to avoid the strength of LSFH to exceed it’s yield limit which will reduce the precision and service life of LSFH, besides when spindle speed reach a extension the weakening influence of the centrifugal force on the radial grip rigidity of the matching of LSFH and cutter should been taken into account. Finally, the finite element analysis results are verified based on the construction of measurement method of the grip rigidity and the results fit very well. The studies provide a theoretical basis for the design, selection and the serialization and standardization of the matching of LSFH and cutter.
基金supported by the National Natural Science Foundation of China(Grant No.51905352)the Natural Science Foundation of Guangdong Province(Grant No.2020A1515011039)+1 种基金the Excellent Science and Technology Creative Talent Training Program of Shenzhen(Grant No.RCBS20210609103819021)the Basic Research Foundation of Shenzhen(Grant No.JCYJ20190808144003701)。
文摘Microstructural functional surfaces play an important role in energy conversion applications including power generation,air conditioning,and thermal management of electronics through the boiling process.In this study,multi-scale microgroove surfaces were fabricated by the combination of wire electrical discharge machining(WEDM)and electrical discharge shaped machining(EDSM)to achieve a better boiling performance.The WEDM,with the advantage of high efficiency,was used to fabricate the first microgroove array,and rougher surfaces were formed by intense discharge.A wavy electrode was used in EDSM to fabricate the second microgroove array.Reentrant cavities at the intersections of microgrooves and rougher micro fins with spacing distribution were formed after EDSM.The boiling performance of the multi-scale microgroove surface was studied with water as the working medium under atmospheric pressure.The results indicated that the boiling performance of the microgroove surface is significantly enhanced.The critical heat flux and maximum heat transfer coefficient of microgroove surface were higher than the surfaces fabricated only by WEDM or EDSM,which were 2.34 and 3.29 times that of smooth copper plate,respectively.This study demonstrated that the combination of WEDM and EDSM is a convenient and effective method to fabricate high-performance microgroove boiling surfaces.
