Current Issue : October-December
Volume : 2021
Issue Number : 4
Articles : 5 Articles
Applying the ultrasonic machining in gear honing can improve honing speed, reduce cutting force, and avoid blocking. *ere are
two problems leading to the decrease of calculation accuracy in the traditional nonresonant theory of the ultrasonic gear honing.
One is that one-dimensional longitudinal vibration theory and two-dimensional theory cannot reflect the vibration characteristics
of ultrasonic horn and gear comprehensively. And, the other one is that the difference of the analysis dimension between the two
theories leads to mismatch of the coupling condition dimension between ultrasonic horn and gear. A free vibration analysis
through Chebyshev–Ritz method based on three-dimensional elasticity theory was presented to analyze the eigenfrequencies of
the horn-gear system in ultrasonic gear honing. In the method, the model of the horn-gear system was divided into four parts: a
solid circular plate, an annular plate, a solid cylinder, and a cone with hole. *e eigenvalue equations were derived by using
displacement coupling condition between each part under completely free boundary condition. It was found that the eigenfrequencies
were highly convergent through convergence study. *e hammering method for a modal experiment was used to test
the horn-gear systems’ eigenfrequencies. And, the finite element method was also applied to solve the eigenfrequencies. *rough a
comparative analysis of the frequencies obtained by these three methods, it showed that the results achieved by the Chebyshev–
Ritz method were close to those obtained from the experiment and finite element method. *us, it was feasible to use the
Chebyshev–Ritz method to solve the eigenfrequencies of the horn-gear system in ultrasonic gear honing....
This paper focuses on modeling the time-varying stiffness of spur gearings, which in
dynamic models of transmission systems acts as an important element of the internal excitation of
the dynamic system. Here are introduced ways to approach the modeling of gear stiffness using
analytical calculations, which allow to model the course of mesh stiffness depending on its rotation.
For verification of used analytical model were created five different gearings, and based on their
geometry, the respective stiffness curves were analytically determined. Subsequently, a finite element
simulation was performed in the Abaqus CAE software. Due to this software, it was possible to
identify and objectively compare the stiffness curves and further determine the suitability of using
the analytical model to determine the mesh stiffness of gearing....
Developing accurate design data to enable the effective use of new materials is undoubtedly
an essential goal in the gear industry. To speed up this process, Single Tooth Bending Fatigue (STBF)
tests can be conducted. However, STBF tests tend to overestimate the material properties with
respect to tests conducted on Running Gears (RG). Therefore, it is common practice to use a constant
correction factor fkorr, of value 0.9 to exploit STBF results to design actual gears, e.g., through ISO
6336. In this paper, the assumption that this coefficient can be considered independent from the gear
material, geometry, and loading condition was questioned, and through the combination of numerical
simulations with a multiaxial fatigue criterion, a method for the calculation of fkorr was proposed.
The implementation of this method using different gear geometries and material properties shows
that fkorr varies with the gears geometrical characteristics, the material fatigue strength, and the load
ratio (R) set in STBF tests. In particular, by applying the Findley criterion, it was found that, for the
same gear geometry, fkorr depends on the material as well. Specifically, fkorr increases with the ratio
between the bending and torsional fatigue limits. Moreover, through this method it was shown that
the characteristics related to the material and the geometry have a relevant effect in determining the
critical point (at the tooth root) where the fracture nucleates....
The constant development of environmental protection causes the necessity to increase
the efficiency of machines. By increasing the efficiency of machines, energy losses can be limited,
leading to lower energy consumption. Friction reduction leads to an increase in efficiency and a
decrease in wear. In this paper, selected surface texturing methods, such as burnishing and abrasive
jet machining, with their limitations are presented. Thanks to those processes, various surface
textures can be obtained. Examples of applications of these methods for friction and wear reduction
+e tribological behavior of Ni-based WC-Co coatings is analyzed. +e coatings were deposited on gray cast iron substrates in a
spray and fuse process using SuperJet Eutalloy deposition equipment, varying the oxygen flow conditions in the flame. +e
crystallographic structure of the coatings was characterized via the X-ray diffraction (XRD) technique. +e microhardness was
measured on the surface and in cross sections of the coatings by means of a Knoop microhardness tester. +e topography and the
morphological characteristics of the coatings and the tribo-surfaces were examined using scanning electron microscopy (SEM)
and confocal microscopy, while the chemical composition was measured by means of energy-dispersive X-ray spectroscopy
(EDS). +e tribological behavior of the coatings was examined via a cohesion-adhesion scratch test, using cross sections of the
coatings. Furthermore, two wear tests were carried out, using the pin-on-disk method under ASTM G99 standard and an ASTM
standard G65 sand/rubber wheel abrasion wear test. +e wear of the coatings showed a close relationship to the porosity in the
metal matrix; since then, in the abrasive wear test, a high porosity is related with lower hardness in the coatings; likewise, a low
hardness is related with a high wear....
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