1995 Vol.8(3)
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1995, 9(3).
Abstract:
The development and application of coated cemented carbide made in China are presented. Three aspects of the coated carbide tool's performance: cutting forces, surface finish and tool life are studied. Furthermore speed-correctin coefficients of the tool are given. On the basis of the modules:essential data base, tools' comparison and inquiry, recommending cutting regimes, experimental curve base and an expert system for tool selection.
The development and application of coated cemented carbide made in China are presented. Three aspects of the coated carbide tool's performance: cutting forces, surface finish and tool life are studied. Furthermore speed-correctin coefficients of the tool are given. On the basis of the modules:essential data base, tools' comparison and inquiry, recommending cutting regimes, experimental curve base and an expert system for tool selection.
1995, 9(3).
Abstract:
A method is presentd for estimating fatigue reliability under varibale loading, which is based on load cycles-fatigue life interference theory as well as cumulative fatigue damage analysis. The basic opinion is that for variable loading, the increment of failure probability produced by each load cycle is determinded by the stress level as well as the damage state at which this load cycle applies. Contrast to "conditionaol reliability-equivalent life methodology", this method calculate the equivalent cycle numebers between different stress levels according to cumulative fatigue damage rule but not equivalent failure probability.
A method is presentd for estimating fatigue reliability under varibale loading, which is based on load cycles-fatigue life interference theory as well as cumulative fatigue damage analysis. The basic opinion is that for variable loading, the increment of failure probability produced by each load cycle is determinded by the stress level as well as the damage state at which this load cycle applies. Contrast to "conditionaol reliability-equivalent life methodology", this method calculate the equivalent cycle numebers between different stress levels according to cumulative fatigue damage rule but not equivalent failure probability.
1995, 9(3).
Abstract:
Cryogenic machining is a new technology which makes use of the special mechanical properties of materials in a cryogenic or a "super cold" state for machining. The control of a cryogenic machining system (CMS) is one of the key problems which need to be solved for practical cryogenic machining. A temperature field control principle is presented which calculates the heat source temperature in the light of the tool temperature field information, and a control model of three-dimensional dynamic temperature field for CMS is established, and the boundary conditions and the heat source of temperature field in orthogonal cutting are discussed. Based on the investigation of the control feature and technique, a prototype system for controlling CMS is created.
Cryogenic machining is a new technology which makes use of the special mechanical properties of materials in a cryogenic or a "super cold" state for machining. The control of a cryogenic machining system (CMS) is one of the key problems which need to be solved for practical cryogenic machining. A temperature field control principle is presented which calculates the heat source temperature in the light of the tool temperature field information, and a control model of three-dimensional dynamic temperature field for CMS is established, and the boundary conditions and the heat source of temperature field in orthogonal cutting are discussed. Based on the investigation of the control feature and technique, a prototype system for controlling CMS is created.
1995, 9(3).
Abstract:
The purpose of this paper is to devise a new model of heat conduction for a body which is totally insulated at its boundary. The essence of the new model is modification of the Founier law in such a way that the resulting heat condution problem will be formulated as an initial value problem with a non-standard partial differential equation. The values of normal derivatives of the heat flux to various orders for all times (t>0) will be determined by the governing partial differential equation and the values of normal derivatives of fluxes of fluxes at the initial time (t=0). We study the properites of this model and demonstrate its validity for a simple one-dimensional case of a thin bar insulated at both ends.
The purpose of this paper is to devise a new model of heat conduction for a body which is totally insulated at its boundary. The essence of the new model is modification of the Founier law in such a way that the resulting heat condution problem will be formulated as an initial value problem with a non-standard partial differential equation. The values of normal derivatives of the heat flux to various orders for all times (t>0) will be determined by the governing partial differential equation and the values of normal derivatives of fluxes of fluxes at the initial time (t=0). We study the properites of this model and demonstrate its validity for a simple one-dimensional case of a thin bar insulated at both ends.
STUDY ON USING SERIAL PIPE TO IMPROVE THE DYNAMIC RESPONSE OF ELECTRO-HYKRAULIC SPEED CONTROL SYSTEM
1995, 9(3).
Abstract:
The mathematical models of electro-hydraulic speed control system using series of pipes is presented. The principle of pipe effection on dynamics of the system is developed. Computer simulation and physical experiment are also carried out. The experimental results show that a right choosing of serial pipe for electro-hydraulic system enables the dynamic response of the system to be improved effectively.
The mathematical models of electro-hydraulic speed control system using series of pipes is presented. The principle of pipe effection on dynamics of the system is developed. Computer simulation and physical experiment are also carried out. The experimental results show that a right choosing of serial pipe for electro-hydraulic system enables the dynamic response of the system to be improved effectively.
1995, 9(3).
Abstract:
The soft terrain spectrum is subdivided into three strands, I.e., the original spectrum, the effective spectrum and the rut spectrum. Accordingly, a device for measurements of all these spectra is developed. Based on its measuring results, a dynamic deformation model of the interaction between vehicle and soft terrain and another model of smoothing the enveloping profile of tyre contact area on soft terrain are proposed for further discussion of forming mechanism of soft terrain spectrum which dominates vehicle vibration.
The soft terrain spectrum is subdivided into three strands, I.e., the original spectrum, the effective spectrum and the rut spectrum. Accordingly, a device for measurements of all these spectra is developed. Based on its measuring results, a dynamic deformation model of the interaction between vehicle and soft terrain and another model of smoothing the enveloping profile of tyre contact area on soft terrain are proposed for further discussion of forming mechanism of soft terrain spectrum which dominates vehicle vibration.
1995, 9(3).
Abstract:
The definitions of the normal chordal tooth thickness and the constant chord in international standard ISO 1122/1-1983(E) are analyzed according to the basic principle of involute cylindrical gear geometry. It is pointed out that in the case of spur gears, the two definitions are respectively identical with generally recognized traditional formulas, but in the case of helical gears, they are respectively contradictory with their traditional formulas. The general principle of the method of the two-point measuring for the tooth thickness of gears is analysized, and the calculation formulas of the two-point measuring for the tooth thickness of the involute helical gear is presented. It is proved theoretically that a constant chord can be measured with the method of the two-point measuring (with the tooth thickness caliper) while normal chordal tooth thickness can not be measured with the tooth thickness caliper (the method of the two-point measuring). The issues of the two definitions of the tooth thickness in the international standard are analysed out again in measuring.
The definitions of the normal chordal tooth thickness and the constant chord in international standard ISO 1122/1-1983(E) are analyzed according to the basic principle of involute cylindrical gear geometry. It is pointed out that in the case of spur gears, the two definitions are respectively identical with generally recognized traditional formulas, but in the case of helical gears, they are respectively contradictory with their traditional formulas. The general principle of the method of the two-point measuring for the tooth thickness of gears is analysized, and the calculation formulas of the two-point measuring for the tooth thickness of the involute helical gear is presented. It is proved theoretically that a constant chord can be measured with the method of the two-point measuring (with the tooth thickness caliper) while normal chordal tooth thickness can not be measured with the tooth thickness caliper (the method of the two-point measuring). The issues of the two definitions of the tooth thickness in the international standard are analysed out again in measuring.
1995, 9(3).
Abstract:
The conditions of conversion from brittle removal mechanism to plastic removal mechanism are studied through analysis of ceramic microstruture and the realtionship between the material removal form and machining unit. By the rational technology program workded out, the plane and cylindrical mirror-like surface machining is successfully achieved and its surface roughness Ra is 0.01～0.03μm after many times of experimental study.
The conditions of conversion from brittle removal mechanism to plastic removal mechanism are studied through analysis of ceramic microstruture and the realtionship between the material removal form and machining unit. By the rational technology program workded out, the plane and cylindrical mirror-like surface machining is successfully achieved and its surface roughness Ra is 0.01～0.03μm after many times of experimental study.
1995, 9(3).
Abstract:
A numerical analysis method has been developed for the prediction of the flow in a cross-flow fan with a casing. The method has no simplifying assumptions regarding the geometry of both the impeller baldes and the casing. Taking into consideration the effect of the boundary layer on the upper wall surface of the casing, the internal flow is analyzed using both the direct boundaty element method and the discrete vortex method by assuming that the flow is two-dimensional, inviscid and incompressible. In order to satisfy Kelven's theorem, vorticity is shed at the trailing edges of each impeller blade, then the discrete vortex method is used to approximate the convection of the free vorticity. Results are given for the cross-flow fan with two different configurations of the casing with an identical impeller.
A numerical analysis method has been developed for the prediction of the flow in a cross-flow fan with a casing. The method has no simplifying assumptions regarding the geometry of both the impeller baldes and the casing. Taking into consideration the effect of the boundary layer on the upper wall surface of the casing, the internal flow is analyzed using both the direct boundaty element method and the discrete vortex method by assuming that the flow is two-dimensional, inviscid and incompressible. In order to satisfy Kelven's theorem, vorticity is shed at the trailing edges of each impeller blade, then the discrete vortex method is used to approximate the convection of the free vorticity. Results are given for the cross-flow fan with two different configurations of the casing with an identical impeller.
1995, 9(3).
Abstract:
An analytical model based on statistical energy analysis (SEA) is developed for the sound pressure levels inside a box-like structure due to wide-band random excitaion applied at a prescribed point on the structure. Some conditions that the sound field inside cavity must adapts to SEA assumes are given. The sound responses inside the box structure for four different input mobilities are predicted using the SEA model and compared with experimental results. On the basis of these results, possible ways of reducing the noise inside the box structure are suggested.
An analytical model based on statistical energy analysis (SEA) is developed for the sound pressure levels inside a box-like structure due to wide-band random excitaion applied at a prescribed point on the structure. Some conditions that the sound field inside cavity must adapts to SEA assumes are given. The sound responses inside the box structure for four different input mobilities are predicted using the SEA model and compared with experimental results. On the basis of these results, possible ways of reducing the noise inside the box structure are suggested.
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