At present, most commercial computer-aided manufacturing （CAM） systems are deficient in efficiency and performances on generating tool path during machining impellers. To solve the problem, this article develops a s...At present, most commercial computer-aided manufacturing （CAM） systems are deficient in efficiency and performances on generating tool path during machining impellers. To solve the problem, this article develops a special software to plan cutting path for ruled surface impellers. An approximation algorithm to generate cutting path for machining integral ruled surface impellers is proposed. By fitting sampling data points of an impeller blade into a curve, a model of ruled surface blade of an impeller is built up. Furthermore, by calculating the points where the cutter axis vector intersects the free-form hub surface of an impeller, problems about, for instance, the ambiguity in calculation and machining the wide blade surface with a short flute cutter are solved. Finally, an integral impeller cutting path is planned by way of an integrated cutter location control algorithm. Simulation and machining tests with an impeller are performed on a 5-axis computer numerically controlled （CNC） mill machine, which shows the feasibility of the proposed algorithm.展开更多
The volute tongue,as the crucial component inducing rotor-stator interaction,is detrimental to unsteady pressure pulsations of centrifugal pumps.In the present paper,to investigate the effect of the volute tongue cut ...The volute tongue,as the crucial component inducing rotor-stator interaction,is detrimental to unsteady pressure pulsations of centrifugal pumps.In the present paper,to investigate the effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump,three volute tongues are obtained through twice cuts,named cases 1,2,3.Twenty measuring points are evenly mounted on periphery of the volute casing to obtain unsteady pressure signals using high response transducers.Pressure amplitudes at the blade passing frequency fBPF and root mean square(rms)values in 0 Hz-500 Hz frequency band are applied to evaluate the cutting effect.Results show that pressure spectrum is significantly affected by the volute tongue cut,especially for the component at fBPF.For different measuring points,influences of the volute tongue cut on three cases are not identical.From nns values,it is evident that cutting the volute tongue will lead to pressure energy increasing for most of the concerned measuring points,especially for the points at the far away region from the volute tongue.Finally,from comparison with the original shape case 1,the averaged increment of the twenty points is more than 20%.So it is concluded that for this type centrifugal pump,cutting the volute tongue is not reasonable considering low pressure pulsation requirement.展开更多
基金Key Development Program of Science and Technology of Heilongjiang Province, China (GB05A501)
文摘At present, most commercial computer-aided manufacturing （CAM） systems are deficient in efficiency and performances on generating tool path during machining impellers. To solve the problem, this article develops a special software to plan cutting path for ruled surface impellers. An approximation algorithm to generate cutting path for machining integral ruled surface impellers is proposed. By fitting sampling data points of an impeller blade into a curve, a model of ruled surface blade of an impeller is built up. Furthermore, by calculating the points where the cutter axis vector intersects the free-form hub surface of an impeller, problems about, for instance, the ambiguity in calculation and machining the wide blade surface with a short flute cutter are solved. Finally, an integral impeller cutting path is planned by way of an integrated cutter location control algorithm. Simulation and machining tests with an impeller are performed on a 5-axis computer numerically controlled （CNC） mill machine, which shows the feasibility of the proposed algorithm.
基金Supported by the National Natural Science Foundation of China(Grant Nos.51706086,51576090).
文摘The volute tongue,as the crucial component inducing rotor-stator interaction,is detrimental to unsteady pressure pulsations of centrifugal pumps.In the present paper,to investigate the effect of the volute tongue cut on pressure pulsations of a low specific speed centrifugal pump,three volute tongues are obtained through twice cuts,named cases 1,2,3.Twenty measuring points are evenly mounted on periphery of the volute casing to obtain unsteady pressure signals using high response transducers.Pressure amplitudes at the blade passing frequency fBPF and root mean square(rms)values in 0 Hz-500 Hz frequency band are applied to evaluate the cutting effect.Results show that pressure spectrum is significantly affected by the volute tongue cut,especially for the component at fBPF.For different measuring points,influences of the volute tongue cut on three cases are not identical.From nns values,it is evident that cutting the volute tongue will lead to pressure energy increasing for most of the concerned measuring points,especially for the points at the far away region from the volute tongue.Finally,from comparison with the original shape case 1,the averaged increment of the twenty points is more than 20%.So it is concluded that for this type centrifugal pump,cutting the volute tongue is not reasonable considering low pressure pulsation requirement.
