The wear failure course of gas-valve/valve-seat in engine was investigated with a simulating tester. The results show that the failure of the contact conical surface is mainly caused by the elastic and plastic deforma...The wear failure course of gas-valve/valve-seat in engine was investigated with a simulating tester. The results show that the failure of the contact conical surface is mainly caused by the elastic and plastic deformation and the fatigue micro-crack and spalling. The creep-deformation and corrosion atmosphere accelerated wear failure course at the high temperature. The wear failure course of the gas-valve/valve-seat in engine follows general wear rules of mechanical elements, but the rate of wear in the sharp wear stage is faster.展开更多
The aim of this work was to investigate the sliding wear coefficient k, using an experimental sliding wear study on the valve-seat insert contact. Commercial inlet valve and seat inserts were used as test specimens. T...The aim of this work was to investigate the sliding wear coefficient k, using an experimental sliding wear study on the valve-seat insert contact. Commercial inlet valve and seat inserts were used as test specimens. The tests were performed at room temperature and at 200℃, using test duration of 72,000 cycles and 18,000 cycles, respectively, and both in dry sliding conditions. A load of 5 N, an average speed of 22 mm/s and sliding distance of 2.2 mm were used for all tests. The sliding wear coefficients were calculated using experimental and analytical methods. The wear volume was higher in the tests at 200℃ both in valve and seat insert specimens. The principal wear mechanisms observed in valve specimen were oxidation and abrasion.展开更多
CAPP(Computer Aided Process Planning) has already become the bottleneck of CAD/CAM system.Present two- dimensional CAPP system which is used in the enterprise needs to be input information and data again,because it ca...CAPP(Computer Aided Process Planning) has already become the bottleneck of CAD/CAM system.Present two- dimensional CAPP system which is used in the enterprise needs to be input information and data again,because it can not draw data from CAD(Computer Aided Design) model automatically after building CAD model and drawing.This has influenced extensive use of CAPP system because of its low efficiency.In this paper,three-dimensional model is built by using the parametric method, the process file cart be produced directly through drawing corresponding characteristic and parameter from the model with the aid of process database.This improves the efficiency of product development.Visual C++6.0 and SQL Server 2000 are used to devel- op WTJDCAPP prototype system based on component model and SolidWorks three-dimensional CAD platform.Engine valve-seat is taken as concrete object to validate of the technology.展开更多
The aim of this work was to carry out a sensitivity analysis of a valve recession model. For the sensitivity study, the effects of the parameters on the valve recession model were investigated, for both, light duty an...The aim of this work was to carry out a sensitivity analysis of a valve recession model. For the sensitivity study, the effects of the parameters on the valve recession model were investigated, for both, light duty and heavy duty engines. For light duty engines, it was observed that the impact wear of component parameters had the greatest effect on valve recession and for heavy duty engines, the sliding wear of component parameters had an increasing contribution to the overall valve recession.展开更多
文摘The wear failure course of gas-valve/valve-seat in engine was investigated with a simulating tester. The results show that the failure of the contact conical surface is mainly caused by the elastic and plastic deformation and the fatigue micro-crack and spalling. The creep-deformation and corrosion atmosphere accelerated wear failure course at the high temperature. The wear failure course of the gas-valve/valve-seat in engine follows general wear rules of mechanical elements, but the rate of wear in the sharp wear stage is faster.
文摘The aim of this work was to investigate the sliding wear coefficient k, using an experimental sliding wear study on the valve-seat insert contact. Commercial inlet valve and seat inserts were used as test specimens. The tests were performed at room temperature and at 200℃, using test duration of 72,000 cycles and 18,000 cycles, respectively, and both in dry sliding conditions. A load of 5 N, an average speed of 22 mm/s and sliding distance of 2.2 mm were used for all tests. The sliding wear coefficients were calculated using experimental and analytical methods. The wear volume was higher in the tests at 200℃ both in valve and seat insert specimens. The principal wear mechanisms observed in valve specimen were oxidation and abrasion.
文摘CAPP(Computer Aided Process Planning) has already become the bottleneck of CAD/CAM system.Present two- dimensional CAPP system which is used in the enterprise needs to be input information and data again,because it can not draw data from CAD(Computer Aided Design) model automatically after building CAD model and drawing.This has influenced extensive use of CAPP system because of its low efficiency.In this paper,three-dimensional model is built by using the parametric method, the process file cart be produced directly through drawing corresponding characteristic and parameter from the model with the aid of process database.This improves the efficiency of product development.Visual C++6.0 and SQL Server 2000 are used to devel- op WTJDCAPP prototype system based on component model and SolidWorks three-dimensional CAD platform.Engine valve-seat is taken as concrete object to validate of the technology.
文摘The aim of this work was to carry out a sensitivity analysis of a valve recession model. For the sensitivity study, the effects of the parameters on the valve recession model were investigated, for both, light duty and heavy duty engines. For light duty engines, it was observed that the impact wear of component parameters had the greatest effect on valve recession and for heavy duty engines, the sliding wear of component parameters had an increasing contribution to the overall valve recession.
