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Load-capacity has always been one of the performances that is paid much attention to in the development of bevel gear transmission applications. Consequently, the mathematical model of novel bevel gear with high load-capacity based on geometric elements is proposed in this paper, which could be applied to the aviation, aerospace and other fields. In parallel, the design principle and design method of the novel bevel gear are introduced in detail. Subsequently, the conditions for tooth surface continuity and non-interference are derived. Furthermore, the model of novel bevel gear is established. Finally, the load-bearing characteristics are analyzed, revealing that an increase in the number of contact points could significantly enhance the load capacity of the bevel gear pairs. When the load torque applied to bevel gear II is 100 Nm, the contact pressure endured by the bevel gear pair with five-point contact is decreased by 41.37% compared to the bevel gear pair with single-point contact. When the number of contact points is the same, increasing the distance between the contact points could also reduce the contact stress. This provides strong theoretical support for the application of the bevel gear based on the geometric elements. [ABSTRACT FROM AUTHOR]

Obtaining the load distribution and radial deformations of planetary roller screw mechanism (PRSM) for the load carrying capacity design under complex loading conditions (multi-directional loads) is beneficial to decelerate fatigue and wear of threads. However, the combined effects of axial load, radial load and turning torque (overturning moment) were ignored in previous studies due to the complicated structure of PRSM. This paper presents a multi-roller beam-bar-spring (MR-BBS) model that incorporate radial load, turning torque and thread modification. The proposed model extended the theoretic method for calculating bending behavior of screw and rollers, which can more precisely describe the locus of the threads and roller axis. The load distribution of threads and load sharing among rollers of a PRSM under different external loads and cycling process are analyzed. The results show that the load distribution is more sensitive to turning torque of screw but relatively insensitive to the radial load. Moreover, the load distribution moderately changes with the variation of modification factor. Based on thread modification, the variable lead PRSM is proposed so that the uniformity of load sharing with complex load can be optimized. A multi-roller beam-bar-spring (MR-BBS) model is developed that incorporate axial load, radial load, turning torque and thread modification. The load distribution of threads and load sharing among rollers of a PRSM under different external loads and cycling process are analyzed. The load distribution is more sensitive to turning torque of screw but relatively insensitive to the radial load. The variable lead PRSM is proposed so that the uniformity of load sharing with complex load can be optimized. [ABSTRACT FROM AUTHOR]

The moving mechanism configuration has a major impact on the static stability,dynamic stability and driving force of the wheeled service robot. Taking the six-wheel mobile underpan as the object,the relationships between the wheel layout and the static stability,dynamic stability,driving force to cross obstacle and turn are analyzed. A multi-objective optimization model for wheel layout is established and the optimal solution is derived by using MATLAB genetic algorithm toolbox. Assuming the factors of pitch angle,roll angle and drive torque as evaluation indicators,motion simulation of the mobile underpan is carried out by the virtual prototyping technology. The results show that the pitch angle and roll angle after optimization are decreased by17. 6% and 27. 2%,respectively. The average value and mean square of drive torque are decreased by 2. 8%and 3. 6%,respectively. It is beneficial to the transmission performance and endurance of the mobile underpan. The results also verify the correctness and validity of the established multi-objective optimization model.

As a key component in fields such as high-precision machine tools, aerospace and weaponry, the thermal deformations in a differential planetary roller screw (DPRS) caused by the changes in ambient temperatures can lead to uneven load distribution and increased wear, which can seriously affect its transmission accuracy, efficiency, and service life. Therefore, the temperature rise of a DPRS at different ambient temperatures was studied using the block thermal network method, and the thermal deformations were calculated. A load distribution model of DPRS considering thermal deformation was developed, and a wear prediction method combined with surface roughness was proposed. The results show that the increase in ambient temperature has an obvious negative effect on the load distribution and wear depth of DPRS. Moreover, the DPRS temperature rise, load distribution and wear depth dramatically change with the variation of parameters such as load, speed and thread pitch. A DPRS durability test device that considers changes in ambient temperature was developed. Experiments with temperature rise and DPRS wear under different ambient temperatures were conducted to validate the theoretical analysis model. [ABSTRACT FROM AUTHOR]

The 3 D model of worm and helical gear is established based on UG by the equation of tooth surface and the data point. On the basis of Hyper Mesh,the pretreatment of the finite element model including mesh generation,applying constrains,setting contact condition,etc. is carried out. By using FEM,the analysis of dynamic contact from the double teeth-meshing to the single teeth-meshing and then to the double teeth-meshing is carried out to simulate the changes of the tooth contact stress and shape under the actual working conditions and to find the characteristics of engagement about plastic worm and steel helical gear,steel worm and steel helical gear. The samples including steel helical gear,plastic worm and steel worm are machined by hobbing,injection and turning respectively,then used to wear test on the basic of the micro-transmission test platform,the results show that the contact stress and fluctuation in the meshing process of plastic worm is small,and it has the better wear resistance.