CBN (Cubic Boron Nitride) is a highly efficient abrasive and has unique properties (highhardness, high thermal stability and high chemical inertia). As early as 1969 CBN Wheels had al-ready been made and showed excell...CBN (Cubic Boron Nitride) is a highly efficient abrasive and has unique properties (highhardness, high thermal stability and high chemical inertia). As early as 1969 CBN Wheels had al-ready been made and showed excellent performance for grainding high speed steels and othermaterials hard to be ground. So far, however, CBN Wheels are still not popularly utilized in theindustry, the writer considers the main reason being the inadequate study for practical applica-tions and especially the suitable dressing technique. The dressing of resinoid CBN Wheels discussed in the paper, is different from that ofconventional ones. It has to be divided into two operations, truing and sharpening, each of whichhas its specific and independent functions. A simple dressing method with a lot of informationsuitable for production is studied; finally, the grain height protruding from the bond is taken asan index for evaluating the dressing results, and the effect of grain height on the grinding per-formance is discussed. By selecting proper conditions according to the workpiece requirements, abetter technical and economical benifit can be obtained.展开更多
Most of the mechanical dressing technologies for resin bonded superabrasive grinding wheels are time consumingand costly. Based on the outcomes of the simulations in the previous study, this paper demonstrates the com...Most of the mechanical dressing technologies for resin bonded superabrasive grinding wheels are time consumingand costly. Based on the outcomes of the simulations in the previous study, this paper demonstrates the comprehensive researches on the laser-assisted dressing process control, grinding wheel topography reconfiguration by 3Dlaser scanning technology and analyses of grinding temperature. The synthesized parameter incorporates the laserdressing process parameters and can be used to the process control. In order to evaluate the laser-assisted dressingeffectiveness, the newly developed non-contact laser measuring system based on the principle of the triangulationwas used. Grain protrusion height and intergrain spacing can characterize the grinding wheel surface. A series ofgrinding tests with the laser-assisted dressed grinding wheel and mechanically dressed grinding wheel were conductedfor comparison. The results proved the feasibility of laser-assisted dressing for resin bonded superabrasive grindingwheels and revealed the importance of choosing appropriate laser dressing parameters.展开更多
The purpose of this study is to develop a twin wheel creep-feed grinding machine using continuous dressing to machine precise axisymmetric turbine blades that have been difficult to machine using a conventional creep-...The purpose of this study is to develop a twin wheel creep-feed grinding machine using continuous dressing to machine precise axisymmetric turbine blades that have been difficult to machine using a conventional creep-feed machine.In order to develop such a machine,3D-modeling and machine simulations were performed and a twin wheel creep-feed grinding machine was manufactured.Furthermore,the axisymmetric precision of the machined workpieces through practical machining was evaluated and the quality of the continuous dressing effect of the developed machine was established.In addition,experimental considerations for a proper dresser-to-wheel speed ratio and proper feed rate of the dresser were carried out.As a result,a twin wheel creep-feed grinding machine with continuous dressing is developed through machine simulation,manufacturing and performance evaluation.Optimum condition for the dresser feed rate is 0.3μm/rev.In cases of large dressor-to-wheel speed ratio,grinding efficiency can be enhanced,but the surface roughness shows a conflicting trend.Developed twin wheel creep-feed grinding machine has satisfactory appraisal with regard to surface roughness,flatness,and parallelism.Satisfactory surface roughness below 0.1μm can be obtained for the blade of aircraft.However,in order to perform precise machining,it is necessary to improve the structure of the twin wheel creep-feed grinding machine.展开更多
Precision grinding is a key process for realizing the use of large-aperture aspherical optical elements in laser nuclear fusion devices,large-aperture astronomical telescopes,and high-resolution space cameras.In this ...Precision grinding is a key process for realizing the use of large-aperture aspherical optical elements in laser nuclear fusion devices,large-aperture astronomical telescopes,and high-resolution space cameras.In this study,the arc envelope grinding process of large-aperture aspherical optics is investigated using a CM1500 precision grinding machine with a maximum machinable diameter ofΦ1500 mm.The form error of the aspherical workpiece induced by wheel setting errors is analytically modeled for both parallel and cross grinding.Results show that the form error is more sensitive to the wheel setting error along the feed direction than that along the lateral direction.It is a bilinear function of the feed-direction wheel setting error and the distance to the optical axis.Based on the error function above,a method to determine the wheel setting error is proposed.Subsequently,grinding tests are performed with the wheels aligned accurately.Using a newly proposed partial error compensation method with an appropriate compensation factor,a form error of 3.4μm peak-to-valley(PV)for aΦ400 mm elliptical K9 glass surface is achieved.展开更多
The selected modifications to the construction of grinding wheels were described which facilitate an increase in the material removal rate （grinding wheels with conic chamfer and grinding wheels with microdiscontinui...The selected modifications to the construction of grinding wheels were described which facilitate an increase in the material removal rate （grinding wheels with conic chamfer and grinding wheels with microdiscontinuities on the active surface）. Using these background details, a suggested thesis was put forward regarding the need to develop a device which will allow for the shaping of the macrogeometry of the grinding wheel （cylindrical and conical surfaces） and the microdiscontinuities within the dressing operation simultaneously. The device was presented and prepared in two functional variants （horizontal and vertical mounting of the motor）, then a prototype was described. An example of the grinding wheel active surface, shaped by using this device, was also presented. The theoretical analysis and experimental verification performed determine that the error of shaping the conic chamfer angle within the range of 0-1.5°, using the developed device, is approximately ±3%.展开更多
The technology of superabrasive grinding has been developed in order to achieve high-quality finish in extremely hard and brittle materials.Thereafter, truing and dressing technology on super abrasive grinding wheel i...The technology of superabrasive grinding has been developed in order to achieve high-quality finish in extremely hard and brittle materials.Thereafter, truing and dressing technology on super abrasive grinding wheel is one of the most important subjects on precise machining field at present.In this paper, mist-jetting electrical discharge technology was applied to dressing metal-bonded superabrasive wheels.And a systematical study on the mechanism of selective removal of the bond was proposed.Experiments on dressing bronze bonded diamond grind wheels were carried out on a die-sinking electrical discharge machine.The diamond wheel topographies before and after electrical discharge dressing were observed by VH-800 3D digital microscope.The wheel profiles before and after dressing were observed.The results of electrical discharge dressing under different electrical parameters were compared.Experimental results indicate that the favorable surface topography can be obtained under suitable processing parameters and mist-jetting electrical discharge dressing(MEDD) is feasible for metal-bonded diamond grinding wheel.展开更多
文摘CBN (Cubic Boron Nitride) is a highly efficient abrasive and has unique properties (highhardness, high thermal stability and high chemical inertia). As early as 1969 CBN Wheels had al-ready been made and showed excellent performance for grainding high speed steels and othermaterials hard to be ground. So far, however, CBN Wheels are still not popularly utilized in theindustry, the writer considers the main reason being the inadequate study for practical applica-tions and especially the suitable dressing technique. The dressing of resinoid CBN Wheels discussed in the paper, is different from that ofconventional ones. It has to be divided into two operations, truing and sharpening, each of whichhas its specific and independent functions. A simple dressing method with a lot of informationsuitable for production is studied; finally, the grain height protruding from the bond is taken asan index for evaluating the dressing results, and the effect of grain height on the grinding per-formance is discussed. By selecting proper conditions according to the workpiece requirements, abetter technical and economical benifit can be obtained.
基金This work was supported by the National Natural Science Foundation of China under grant No.59705014 and No.50275095.
文摘Most of the mechanical dressing technologies for resin bonded superabrasive grinding wheels are time consumingand costly. Based on the outcomes of the simulations in the previous study, this paper demonstrates the comprehensive researches on the laser-assisted dressing process control, grinding wheel topography reconfiguration by 3Dlaser scanning technology and analyses of grinding temperature. The synthesized parameter incorporates the laserdressing process parameters and can be used to the process control. In order to evaluate the laser-assisted dressingeffectiveness, the newly developed non-contact laser measuring system based on the principle of the triangulationwas used. Grain protrusion height and intergrain spacing can characterize the grinding wheel surface. A series ofgrinding tests with the laser-assisted dressed grinding wheel and mechanically dressed grinding wheel were conductedfor comparison. The results proved the feasibility of laser-assisted dressing for resin bonded superabrasive grindingwheels and revealed the importance of choosing appropriate laser dressing parameters.
基金Work supported by the Second Stage of Brain Korea 21 Project
文摘The purpose of this study is to develop a twin wheel creep-feed grinding machine using continuous dressing to machine precise axisymmetric turbine blades that have been difficult to machine using a conventional creep-feed machine.In order to develop such a machine,3D-modeling and machine simulations were performed and a twin wheel creep-feed grinding machine was manufactured.Furthermore,the axisymmetric precision of the machined workpieces through practical machining was evaluated and the quality of the continuous dressing effect of the developed machine was established.In addition,experimental considerations for a proper dresser-to-wheel speed ratio and proper feed rate of the dresser were carried out.As a result,a twin wheel creep-feed grinding machine with continuous dressing is developed through machine simulation,manufacturing and performance evaluation.Optimum condition for the dresser feed rate is 0.3μm/rev.In cases of large dressor-to-wheel speed ratio,grinding efficiency can be enhanced,but the surface roughness shows a conflicting trend.Developed twin wheel creep-feed grinding machine has satisfactory appraisal with regard to surface roughness,flatness,and parallelism.Satisfactory surface roughness below 0.1μm can be obtained for the blade of aircraft.However,in order to perform precise machining,it is necessary to improve the structure of the twin wheel creep-feed grinding machine.
基金Fellowship of China National Postdoctoral Program for Innovative Talents(Grant No.BX20200268)Research Project of State Key Laboratory of Mechanical System and Vibration(Grant No.MSV202103)+1 种基金National Natural Science Foundation of China(Grant No.51720105016)Higher Education Discipline Innovation Project(Grant No.B12016).
文摘Precision grinding is a key process for realizing the use of large-aperture aspherical optical elements in laser nuclear fusion devices,large-aperture astronomical telescopes,and high-resolution space cameras.In this study,the arc envelope grinding process of large-aperture aspherical optics is investigated using a CM1500 precision grinding machine with a maximum machinable diameter ofΦ1500 mm.The form error of the aspherical workpiece induced by wheel setting errors is analytically modeled for both parallel and cross grinding.Results show that the form error is more sensitive to the wheel setting error along the feed direction than that along the lateral direction.It is a bilinear function of the feed-direction wheel setting error and the distance to the optical axis.Based on the error function above,a method to determine the wheel setting error is proposed.Subsequently,grinding tests are performed with the wheels aligned accurately.Using a newly proposed partial error compensation method with an appropriate compensation factor,a form error of 3.4μm peak-to-valley(PV)for aΦ400 mm elliptical K9 glass surface is achieved.
文摘The selected modifications to the construction of grinding wheels were described which facilitate an increase in the material removal rate （grinding wheels with conic chamfer and grinding wheels with microdiscontinuities on the active surface）. Using these background details, a suggested thesis was put forward regarding the need to develop a device which will allow for the shaping of the macrogeometry of the grinding wheel （cylindrical and conical surfaces） and the microdiscontinuities within the dressing operation simultaneously. The device was presented and prepared in two functional variants （horizontal and vertical mounting of the motor）, then a prototype was described. An example of the grinding wheel active surface, shaped by using this device, was also presented. The theoretical analysis and experimental verification performed determine that the error of shaping the conic chamfer angle within the range of 0-1.5°, using the developed device, is approximately ±3%.
基金the National Natural Science Foundation of China (No. 50775143)the Research Fundfor the Doctoral Program of Higher Education(No. 20060248031)the User program of Research Developing Center of Manufacturing Technology and Automatic Equipment
文摘The technology of superabrasive grinding has been developed in order to achieve high-quality finish in extremely hard and brittle materials.Thereafter, truing and dressing technology on super abrasive grinding wheel is one of the most important subjects on precise machining field at present.In this paper, mist-jetting electrical discharge technology was applied to dressing metal-bonded superabrasive wheels.And a systematical study on the mechanism of selective removal of the bond was proposed.Experiments on dressing bronze bonded diamond grind wheels were carried out on a die-sinking electrical discharge machine.The diamond wheel topographies before and after electrical discharge dressing were observed by VH-800 3D digital microscope.The wheel profiles before and after dressing were observed.The results of electrical discharge dressing under different electrical parameters were compared.Experimental results indicate that the favorable surface topography can be obtained under suitable processing parameters and mist-jetting electrical discharge dressing(MEDD) is feasible for metal-bonded diamond grinding wheel.
