1988 Vol.1(1)
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1988, 2(1).
Abstract:
The wear resistance of 28Cr cast iron having different matrices was studied by pin-disk abrasion test using two kinds of abrasives (green SiC and garnet). It was shown that 28Cr white cast iron can be successfully used in the as-cast condition. Furthermore, the abrasion-corrosion wear resistance of as-cast 28Cr iron and martensitic 15Cr1MolCu cast iron were compared in media with different pH values. Results showed that copper alloyed 28Cr cast iron is more competitive than 15CrMo1Cu cast iron in certain environments. In addition, the mechanical properties of 28Cr cast iron with different pH matrices and different carbon contents were measured in order to provide a basis for engineering applications.
The wear resistance of 28Cr cast iron having different matrices was studied by pin-disk abrasion test using two kinds of abrasives (green SiC and garnet). It was shown that 28Cr white cast iron can be successfully used in the as-cast condition. Furthermore, the abrasion-corrosion wear resistance of as-cast 28Cr iron and martensitic 15Cr1MolCu cast iron were compared in media with different pH values. Results showed that copper alloyed 28Cr cast iron is more competitive than 15CrMo1Cu cast iron in certain environments. In addition, the mechanical properties of 28Cr cast iron with different pH matrices and different carbon contents were measured in order to provide a basis for engineering applications.
1988, 2(1).
Abstract:
The influence of hot deformation conditions on static and dynamic recrystallization behaviour of 12CrNi3A and 18Ni maraqing steels was studied. Using the Zener-Hollomon parameter in the dynamic recrystallization diaqram for reference, a new parameter Y(=tZmexp(-Qrec/RT)) is recommended and a static recrystallization diaqram put forward. The occurrence of static recrystallization of hot deformed austenite in 12CrNi3A and 18Ni carraqing steels was determined as a function of Y parameter(the holding time modified by temperature and stain rate). The structural changes after deformation in hot deformed austenite may be described by the static recrystallization diagram (Y-ε diagram). The procedure for building the static recrystallization diagram may be simplified by introducting the parameter Y, and a simple and east method for building the dynamic recrystallization diagram with log-log scale was recommended.
The influence of hot deformation conditions on static and dynamic recrystallization behaviour of 12CrNi3A and 18Ni maraqing steels was studied. Using the Zener-Hollomon parameter in the dynamic recrystallization diaqram for reference, a new parameter Y(=tZmexp(-Qrec/RT)) is recommended and a static recrystallization diaqram put forward. The occurrence of static recrystallization of hot deformed austenite in 12CrNi3A and 18Ni carraqing steels was determined as a function of Y parameter(the holding time modified by temperature and stain rate). The structural changes after deformation in hot deformed austenite may be described by the static recrystallization diagram (Y-ε diagram). The procedure for building the static recrystallization diagram may be simplified by introducting the parameter Y, and a simple and east method for building the dynamic recrystallization diagram with log-log scale was recommended.
1988, 2(1).
Abstract:
This paper studies first the conjugate action on the transverse plane and calculate (Xp, Yp) the point on transverse path of contact out of (Xp, Yp, Zp) the point on space path of contact. Then studies the normal contact condition of rack and helical gear in the plane normal to the tooth trace of rack and passing through pitch point in order to geq Zp. Consequently we get the three-dimentional cordinates of contact point in fixed space as follows; Xp=－Yptanγ＝－Ytanγ(1)Yp＝Y(2)Zp=Xptanβ1＝－Yptanγtanβ1=h1λ1(3)Where, Y, γ＝ordinate, gradient angle in transvers eplane of auxiliary rack profile meshed with given helical gear1, β1, h1, λ1=helix angle, reduced to a plane gearing. If gear 1 is a helical gear, we must calculate Zp and λ1 with the above formulae. Ater determination (Xp, Yp, Zp) of the contact point, with the aid of screw motion and cordinate transformation, we can calculate the profile of mating helical gear in a very simple way. A hob design prolbem is used as an example and have been proven exactly by actual cutting. This paper also determines the point on line of contact on the rack-tooth surface with the same method.
This paper studies first the conjugate action on the transverse plane and calculate (Xp, Yp) the point on transverse path of contact out of (Xp, Yp, Zp) the point on space path of contact. Then studies the normal contact condition of rack and helical gear in the plane normal to the tooth trace of rack and passing through pitch point in order to geq Zp. Consequently we get the three-dimentional cordinates of contact point in fixed space as follows; Xp=－Yptanγ＝－Ytanγ(1)Yp＝Y(2)Zp=Xptanβ1＝－Yptanγtanβ1=h1λ1(3)Where, Y, γ＝ordinate, gradient angle in transvers eplane of auxiliary rack profile meshed with given helical gear1, β1, h1, λ1=helix angle, reduced to a plane gearing. If gear 1 is a helical gear, we must calculate Zp and λ1 with the above formulae. Ater determination (Xp, Yp, Zp) of the contact point, with the aid of screw motion and cordinate transformation, we can calculate the profile of mating helical gear in a very simple way. A hob design prolbem is used as an example and have been proven exactly by actual cutting. This paper also determines the point on line of contact on the rack-tooth surface with the same method.
1988, 2(1).
Abstract:
This paper gives the experimental correlation of Sh and Nu with Re according to the measured values of vapor diffusion heat transfer when a gas flow containing water vapor flows through a horizontal tube bundle. The conclusion of this paper is that, Rose's numerical correlation can be applied to the mass transfer of the gas flow containing water vapor, and the Stephen flow caused by the condensation of the water vapor in the gas flow increased greatly the convective heat transfer.
This paper gives the experimental correlation of Sh and Nu with Re according to the measured values of vapor diffusion heat transfer when a gas flow containing water vapor flows through a horizontal tube bundle. The conclusion of this paper is that, Rose's numerical correlation can be applied to the mass transfer of the gas flow containing water vapor, and the Stephen flow caused by the condensation of the water vapor in the gas flow increased greatly the convective heat transfer.
1988, 2(1).
Abstract:
In this paper relevant modifications have been made in the earlier developed computer programme for numerical analysis of 2-D axisymmetrical stress-strain cycles caused by GTA spot welding of thin plate. The stress-strain state during welding process in titanium alloy plates has been calculated by using of modified programme and the results of numerical analysis in titanium alloys were given in comparison with those in aluminium alloys and stainless steels as well. Based on these results the specific features of the welding thermal elasto-plastic stress-strain cycles in titanium alloys were characterized. The programme was examined by the Moire technique specially developed for assessing transient weld thermal strains. Good agreement metween calculated results and experimental ones has been achieved, this shows that the computer programme could really describe the two-dimensional stress-strain cycles of thin plate during GTA spot welding process.
In this paper relevant modifications have been made in the earlier developed computer programme for numerical analysis of 2-D axisymmetrical stress-strain cycles caused by GTA spot welding of thin plate. The stress-strain state during welding process in titanium alloy plates has been calculated by using of modified programme and the results of numerical analysis in titanium alloys were given in comparison with those in aluminium alloys and stainless steels as well. Based on these results the specific features of the welding thermal elasto-plastic stress-strain cycles in titanium alloys were characterized. The programme was examined by the Moire technique specially developed for assessing transient weld thermal strains. Good agreement metween calculated results and experimental ones has been achieved, this shows that the computer programme could really describe the two-dimensional stress-strain cycles of thin plate during GTA spot welding process.
1988, 2(1).
Abstract:
The recessed hydrostatic bearing without axial grooves is such a bearing that makes good usr of the dynamic effects on the axial and circumferential lands in order in order to improve the load capacity of the bearing. In this paper the programming of the hydrostatic bearing with any number of recesses is discussed. For the analysis and calculation of the bearing, the Reynolds' equation is directly solved by the Finite Difference Method with imequal steps which is one of the much more general numerical formulation. The Complex Method is applied in the optimum design. The total power dissipation/load capacity is regarded as an objective function. In order to make the optimum design available for use, a series of technical approaches are applied to save computer time, such as higher and/or lower accuracy iteration technique, automatic selection of the superrelaxation factors. The computer program written in FORTRAN 77 for the optimum design is worked out and can be run on the microcomputers such as IBM-PC, MC 68000 which is specially suitable to the conditions in our county.
The recessed hydrostatic bearing without axial grooves is such a bearing that makes good usr of the dynamic effects on the axial and circumferential lands in order in order to improve the load capacity of the bearing. In this paper the programming of the hydrostatic bearing with any number of recesses is discussed. For the analysis and calculation of the bearing, the Reynolds' equation is directly solved by the Finite Difference Method with imequal steps which is one of the much more general numerical formulation. The Complex Method is applied in the optimum design. The total power dissipation/load capacity is regarded as an objective function. In order to make the optimum design available for use, a series of technical approaches are applied to save computer time, such as higher and/or lower accuracy iteration technique, automatic selection of the superrelaxation factors. The computer program written in FORTRAN 77 for the optimum design is worked out and can be run on the microcomputers such as IBM-PC, MC 68000 which is specially suitable to the conditions in our county.
1988, 2(1).
Abstract:
The metal cutting tools are widely employed in machine manufacture, and the cutting angle of the tools is intricate and versatile according to the kinds of workpiece and the conditions of production. But to date there are scarcely and general formulas used to express the regularity of variation for the cutting angle of different cutting tools. In this paper some general formulas of cutting angle are derived in consideration of the direction of cutting speed and the direction of cutting edge and surface normal of tools. By means of these formulas the cutting angle of any complicated tools can be calculated with convenience.
The metal cutting tools are widely employed in machine manufacture, and the cutting angle of the tools is intricate and versatile according to the kinds of workpiece and the conditions of production. But to date there are scarcely and general formulas used to express the regularity of variation for the cutting angle of different cutting tools. In this paper some general formulas of cutting angle are derived in consideration of the direction of cutting speed and the direction of cutting edge and surface normal of tools. By means of these formulas the cutting angle of any complicated tools can be calculated with convenience.
1988, 2(1).
Abstract:
Based on the principle of the stability of microstructure in metallic systems and the cycle dependent property of materials, it is proposed and verified that for cyclic hardening materials, in case of the cycles of the first level of high stress are relatively small under high-low two stress level test, the cumulative fatigue damage ∑ni/Ni is inevitably greater than unity, and it's deduced that such a conclusion should be also true under high-low multi-stress level test. Whereas for cyclic softening materials the cumelative damage is less than unity under high-low two stress livel test. Through a comprehensive analysis to the test results, some suggestions on the caloulation of cumulative fatiguue damage are proposed.
Based on the principle of the stability of microstructure in metallic systems and the cycle dependent property of materials, it is proposed and verified that for cyclic hardening materials, in case of the cycles of the first level of high stress are relatively small under high-low two stress level test, the cumulative fatigue damage ∑ni/Ni is inevitably greater than unity, and it's deduced that such a conclusion should be also true under high-low multi-stress level test. Whereas for cyclic softening materials the cumelative damage is less than unity under high-low two stress livel test. Through a comprehensive analysis to the test results, some suggestions on the caloulation of cumulative fatiguue damage are proposed.
1988, 2(1).
Abstract:
For identification of machine tool dynamical systems, the frequency response method or the mechanical impedance test is applied generally. Its application has got enough success. Now a new identification theory and method for the machine tool dynamical systems is proposed and studied by us. The experiments are completed successfully. Our identification theory and method is to obtain the frequency response data using the complete frequency response testing technuque at first. Through the curve fitting calculation by micro-computer, the transfer matrix of the system is identified. Using the state graphical method, from the transfer matrix, the state space mathematical model of the system is obtained at last.
For identification of machine tool dynamical systems, the frequency response method or the mechanical impedance test is applied generally. Its application has got enough success. Now a new identification theory and method for the machine tool dynamical systems is proposed and studied by us. The experiments are completed successfully. Our identification theory and method is to obtain the frequency response data using the complete frequency response testing technuque at first. Through the curve fitting calculation by micro-computer, the transfer matrix of the system is identified. Using the state graphical method, from the transfer matrix, the state space mathematical model of the system is obtained at last.
1988, 2(1).
Abstract:
To distinguish the real modal from the false one and to identify the modal parameters accurately are two dey problems in applying ITD as an identification technique. The ITD method uses a confidence factor of the modal to distinguish the real from the false, its accuracy is significantly influenced by the noise in the recorded signal and the numbers of the measured points, and the results have to be judged artificially. This method also requires to change the least aquare equations into the form of normal equations to solve the matrix of the systen, which makes a worse ill-condition and instability of the equations to be solved. In order to improve the ITD method, the real and false modals are distinguished by means of the comparison of the frequence values of different series, with which a quite reasonable reliability can be assured even with less measuring points and the influence of the recorded noise on the real modal of the system can be reduced to a minimum extent. An improved Gram-schmit orthogonalization approach is used to solve the least square equations in the identification calculation for a higher precision. An identification program is designed with the FORTRAN77 algorithmic language. With the program several tests are performed with satisfactory results.
To distinguish the real modal from the false one and to identify the modal parameters accurately are two dey problems in applying ITD as an identification technique. The ITD method uses a confidence factor of the modal to distinguish the real from the false, its accuracy is significantly influenced by the noise in the recorded signal and the numbers of the measured points, and the results have to be judged artificially. This method also requires to change the least aquare equations into the form of normal equations to solve the matrix of the systen, which makes a worse ill-condition and instability of the equations to be solved. In order to improve the ITD method, the real and false modals are distinguished by means of the comparison of the frequence values of different series, with which a quite reasonable reliability can be assured even with less measuring points and the influence of the recorded noise on the real modal of the system can be reduced to a minimum extent. An improved Gram-schmit orthogonalization approach is used to solve the least square equations in the identification calculation for a higher precision. An identification program is designed with the FORTRAN77 algorithmic language. With the program several tests are performed with satisfactory results.
1988, 2(1).
Abstract:
In this paper, the method of parabolic modification form is discussed form the theory of mesh, It should be noted that there are some defects in this method and this paper presents chaniging way. The author has given an exact calculating formula of the transmission ratio and all the calculating formulas of meshing index.
In this paper, the method of parabolic modification form is discussed form the theory of mesh, It should be noted that there are some defects in this method and this paper presents chaniging way. The author has given an exact calculating formula of the transmission ratio and all the calculating formulas of meshing index.
1988, 2(1).
Abstract:
A new LT process has been established after the study of Z-1 regenerated salt, the composition of bath, the preferred selection of process parameters, various cxaminations of properties and production practice. The structure of Z-1 regenerated salt, which possesses the quick-action and stability to adjust the content of molten bath, has been analysed by means of infrared spectra. Molten bath and regenerated salt have now been commercialized. By IPM, EDX and X-ray diffraction analyses, it is found that there exit S,N,C and O in the codiffused layer, with Fes-rich being on the surface. From the tribolgical viewpoint, the property of S-N-C codiffusd layer with LT treatment has been investigated, which shows that the hardness gradient conforms with Amontons Law. The LT treated workpieces made of different materials have good anti-friction, anti-seizure, anti-wear and anti-fatigue properties which are of crucial importance to improve the service reliabilities of high-Cr stainless steel frictioal-pairs (e.g.gears and impellers) and 0.45%C steel energy=regulating valves in refregerator, and to increase the life of high-speed steel cuting tools and high-Cr steel dies, which may produce a great economic result. Three compositions of molten bath and methods of ventilation have been established to meet the requirements for various steel workpieces. The process is characteristic not only of stable treatment and extensive application, but also of non-pollution for water and atmosphere.
A new LT process has been established after the study of Z-1 regenerated salt, the composition of bath, the preferred selection of process parameters, various cxaminations of properties and production practice. The structure of Z-1 regenerated salt, which possesses the quick-action and stability to adjust the content of molten bath, has been analysed by means of infrared spectra. Molten bath and regenerated salt have now been commercialized. By IPM, EDX and X-ray diffraction analyses, it is found that there exit S,N,C and O in the codiffused layer, with Fes-rich being on the surface. From the tribolgical viewpoint, the property of S-N-C codiffusd layer with LT treatment has been investigated, which shows that the hardness gradient conforms with Amontons Law. The LT treated workpieces made of different materials have good anti-friction, anti-seizure, anti-wear and anti-fatigue properties which are of crucial importance to improve the service reliabilities of high-Cr stainless steel frictioal-pairs (e.g.gears and impellers) and 0.45%C steel energy=regulating valves in refregerator, and to increase the life of high-speed steel cuting tools and high-Cr steel dies, which may produce a great economic result. Three compositions of molten bath and methods of ventilation have been established to meet the requirements for various steel workpieces. The process is characteristic not only of stable treatment and extensive application, but also of non-pollution for water and atmosphere.
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