As an important green manufacturing process,dry grinding has problems such as high grinding temperature and insufficient cooling capacity.Aiming at the problems of sticking and burns in dry grinding of titanium alloys...As an important green manufacturing process,dry grinding has problems such as high grinding temperature and insufficient cooling capacity.Aiming at the problems of sticking and burns in dry grinding of titanium alloys,grinding performance evaluation of molybdenum disulfide(MoS_(2))solid lubricant coated brazed cubic boron carbide(CBN)grinding wheel(MoS_(2)-coated CBN wheel)in dry grinding titanium alloys was carried out.The lubrication mechanism of MoS_(2)in the grinding process is analyzed,and the MoS_(2)-coated CBN wheel is prepared.The results show that the MoS_(2)solid lubricant can form a lubricating film on the ground surface and reduce the friction coefficient and grinding force.Within the experimental parameters,normal grinding force decreased by 42.5%,and tangential grinding force decreased by 28.1%.MoS_(2)lubricant can effectively improve the heat dissipation effect of titanium alloy grinding arc area.Compared with common CBN grinding wheel,MoS_(2)-coated CBN wheel has lower grinding temperature.When the grinding depth reaches 20μm,the grinding temperature decreased by 30.5%.The wear of CBN grains of grinding wheel were analyzed by mathematical statistical method.MoS_(2)lubricating coating can essentially decrease the wear of grains,reduce the adhesion of titanium alloy chip,prolong the service life of grinding wheel,and help to enhance the surface quality of workpiece.This research provides high-quality and efficient technical support for titanium alloy grinding.展开更多
A creative conception is proposed to enhance heat transfer in grinding contact zone through jet impinging on the basis of analysis on the mechanism of burn during creep feed grinding, and a new apparatus of slotted &a...A creative conception is proposed to enhance heat transfer in grinding contact zone through jet impinging on the basis of analysis on the mechanism of burn during creep feed grinding, and a new apparatus of slotted & perforated electroplated CBN grinding wheel with radial jet is developed, the effect on heat transfer is studied through the experiment of intermitted creep feed grinding. Experimental results show that the technology of enhancing heat transfer through jet impinging is valid to raise the efficiency of heat transfer in grinding contact zone and it is widely applied to solve the problem in grinding burn for difficult to machine materials.展开更多
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
The burning mechanism during creep feed grinding of titanium alloy with SiC wheel is stud- ied. A CBN intermittent creep feed grinding technology combining the advantages of CBN, intermittent grinding and creep feed ...The burning mechanism during creep feed grinding of titanium alloy with SiC wheel is stud- ied. A CBN intermittent creep feed grinding technology combining the advantages of CBN, intermittent grinding and creep feed grinding is recommended. The results show that the intermittent CBN wheel has a bright future in resolving the problem of workpiece burning during creep feed grinding of titanium al- loys展开更多
The machining surface integrity of aero-engine turbine disc slots has a significant impact on their fatigue life and service performance,and achieving efficiency and high-precision machining is still a great challenge...The machining surface integrity of aero-engine turbine disc slots has a significant impact on their fatigue life and service performance,and achieving efficiency and high-precision machining is still a great challenge.The high machining requirements of future aeroengine turbine disc slots will be difficult to satisfy using the broaching method.In addition,existing methods of slot machin-ing face difficulties in ensuring surface integrity.This study explored a cup shaped electroplated Cubic Boron Nitride(CBN)abrasive wheel for profile grinding the turbine disc slots of FGH96 powder metallurgy superalloy.The matrix structure of the cup shaped abrasive wheel was designed and verified.A profile grinding experiment was conducted for fir-tree slots on a five-axis machining center.The accuracy and the surface integrity were analyzed.Results show that the key dimension detection results of the slots were within the allowable tolerance range.Meanwhile,an average sur-face roughness Ra of 0.55μm was achieved,the residual stress was compressive,the plastic defor-mation layer thickness was less than 5μm,and the hardening layer thickness was less than 20μm.The research findings provide a new approach to machining the slots of aviation engine turbine discs and guidance for the high-quality processing of complex components.展开更多
In order to develop the high-efficiency and precision machining technique of TiCp/Ti - 6Al-4V particulate reinforced titanium matrix composites (PTMCs), high-speed grinding experiments were conducted using the singl...In order to develop the high-efficiency and precision machining technique of TiCp/Ti - 6Al-4V particulate reinforced titanium matrix composites (PTMCs), high-speed grinding experiments were conducted using the single-layer electroplated cubic boron nitride (CBN) wheel and brazed CBN wheel, respectively. The comparative grinding performance was studied in terms of grinding force, grinding temperature, grinding-induced surface features and defects. The results display that the grinding forces and grinding temperature obtained with the brazed CBN wheel are always lower than those with the electroplated CBN wheel. Though the voids and microcracks are the dominant grinding-induced surface defects, the brazed CBN wheel produces less surface defects compared to the electroplated wheel according to the statistical analysis results. The max mum materials removal rate with the brazed CBN wheel is much higher than that with the electroplated one. All above indicate that the single-layer brazed CBN super-abrasive wheel is more suitable for high-speed grinding of PTMCs than the electroplated counterpart.展开更多
Internal cylindrical grinding is much more difficult than other grindings, because of its lowproductivity and poor quality, e. g. taper often occurs in hole after grinding, which has an effect onthe service life of th...Internal cylindrical grinding is much more difficult than other grindings, because of its lowproductivity and poor quality, e. g. taper often occurs in hole after grinding, which has an effect onthe service life of the workpiece. It is a pity that internal cylindrical grinding is rarely studied. Inthis paper. aimed at the above conditions, factors affecting the accuracy of internal cylindricalgrinding are theoretically analyzed. The roller shell of the ring spinning frame(as mass part)aretaken as an example, of which internal cylindrical grinding tests are made. Tests show that thetheory conforms with practice.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.92160301,92060203,52175415,52205475)Science Center for Gas Turbine Project of China(Grant Nos.P2022-AB-IV-002-001,P2023-B-IV-003-001)+1 种基金Jiangsu Provincial Natural Science Foundation of China(Grant No.BK20210295)Graduate Research and Innovation Projects in Jiangsu Province of China(Grant No.KYCX22_0339).
文摘As an important green manufacturing process,dry grinding has problems such as high grinding temperature and insufficient cooling capacity.Aiming at the problems of sticking and burns in dry grinding of titanium alloys,grinding performance evaluation of molybdenum disulfide(MoS_(2))solid lubricant coated brazed cubic boron carbide(CBN)grinding wheel(MoS_(2)-coated CBN wheel)in dry grinding titanium alloys was carried out.The lubrication mechanism of MoS_(2)in the grinding process is analyzed,and the MoS_(2)-coated CBN wheel is prepared.The results show that the MoS_(2)solid lubricant can form a lubricating film on the ground surface and reduce the friction coefficient and grinding force.Within the experimental parameters,normal grinding force decreased by 42.5%,and tangential grinding force decreased by 28.1%.MoS_(2)lubricant can effectively improve the heat dissipation effect of titanium alloy grinding arc area.Compared with common CBN grinding wheel,MoS_(2)-coated CBN wheel has lower grinding temperature.When the grinding depth reaches 20μm,the grinding temperature decreased by 30.5%.The wear of CBN grains of grinding wheel were analyzed by mathematical statistical method.MoS_(2)lubricating coating can essentially decrease the wear of grains,reduce the adhesion of titanium alloy chip,prolong the service life of grinding wheel,and help to enhance the surface quality of workpiece.This research provides high-quality and efficient technical support for titanium alloy grinding.
文摘A creative conception is proposed to enhance heat transfer in grinding contact zone through jet impinging on the basis of analysis on the mechanism of burn during creep feed grinding, and a new apparatus of slotted & perforated electroplated CBN grinding wheel with radial jet is developed, the effect on heat transfer is studied through the experiment of intermitted creep feed grinding. Experimental results show that the technology of enhancing heat transfer through jet impinging is valid to raise the efficiency of heat transfer in grinding contact zone and it is widely applied to solve the problem in grinding burn for difficult to machine materials.
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.
文摘The burning mechanism during creep feed grinding of titanium alloy with SiC wheel is stud- ied. A CBN intermittent creep feed grinding technology combining the advantages of CBN, intermittent grinding and creep feed grinding is recommended. The results show that the intermittent CBN wheel has a bright future in resolving the problem of workpiece burning during creep feed grinding of titanium al- loys
基金supported by the National Natural Science Foundation of China (Nos.52305477,52375447,52305474)Major Special Projects of Aero-engine and Gas Turbine (No.2017-VII-0002-0095)+4 种基金the Special Fund of Taishan Scholars Project (No.tsqn202211179)the Youth Talent Promotion Project in Shandong (No.SDAST2021qt12)the Natural Science Foundation of Shandong Province (Nos.ZR2023QE057,ZR2022QE028,ZR2021QE116,and ZR2020KE027)Qingdao Science and Technology Planning Park Cultivation Plan (No.23-1-5-yqpy-17-qy)the Natural Science Foundation of Jiangsu Province (No.BK20210407).
文摘The machining surface integrity of aero-engine turbine disc slots has a significant impact on their fatigue life and service performance,and achieving efficiency and high-precision machining is still a great challenge.The high machining requirements of future aeroengine turbine disc slots will be difficult to satisfy using the broaching method.In addition,existing methods of slot machin-ing face difficulties in ensuring surface integrity.This study explored a cup shaped electroplated Cubic Boron Nitride(CBN)abrasive wheel for profile grinding the turbine disc slots of FGH96 powder metallurgy superalloy.The matrix structure of the cup shaped abrasive wheel was designed and verified.A profile grinding experiment was conducted for fir-tree slots on a five-axis machining center.The accuracy and the surface integrity were analyzed.Results show that the key dimension detection results of the slots were within the allowable tolerance range.Meanwhile,an average sur-face roughness Ra of 0.55μm was achieved,the residual stress was compressive,the plastic defor-mation layer thickness was less than 5μm,and the hardening layer thickness was less than 20μm.The research findings provide a new approach to machining the slots of aviation engine turbine discs and guidance for the high-quality processing of complex components.
基金the financial support for this work by the National Natural Science Foundation of China (No.51235004 and No.51375235)the Fundamental Research Funds for the Central Universities (No.NE2014103)the Science and Technology Supporting Program of Jiangsu Province (No.BE2013109 and No.BY2014003-008)
文摘In order to develop the high-efficiency and precision machining technique of TiCp/Ti - 6Al-4V particulate reinforced titanium matrix composites (PTMCs), high-speed grinding experiments were conducted using the single-layer electroplated cubic boron nitride (CBN) wheel and brazed CBN wheel, respectively. The comparative grinding performance was studied in terms of grinding force, grinding temperature, grinding-induced surface features and defects. The results display that the grinding forces and grinding temperature obtained with the brazed CBN wheel are always lower than those with the electroplated CBN wheel. Though the voids and microcracks are the dominant grinding-induced surface defects, the brazed CBN wheel produces less surface defects compared to the electroplated wheel according to the statistical analysis results. The max mum materials removal rate with the brazed CBN wheel is much higher than that with the electroplated one. All above indicate that the single-layer brazed CBN super-abrasive wheel is more suitable for high-speed grinding of PTMCs than the electroplated counterpart.
文摘Internal cylindrical grinding is much more difficult than other grindings, because of its lowproductivity and poor quality, e. g. taper often occurs in hole after grinding, which has an effect onthe service life of the workpiece. It is a pity that internal cylindrical grinding is rarely studied. Inthis paper. aimed at the above conditions, factors affecting the accuracy of internal cylindricalgrinding are theoretically analyzed. The roller shell of the ring spinning frame(as mass part)aretaken as an example, of which internal cylindrical grinding tests are made. Tests show that thetheory conforms with practice.