In this investigation, the effect of revolute joints’ clearance on the dynamic performance of mechanical systems is reported. A computation algorithm is developed with the aid of SolidWorks/CosmosMotion software package. A slider-crank mechanism with one and two clearance-joints is studied and analyzed when working in vertical and in horizontal planes. The simulation results point out that the presence of such clearance in the joints of the system understudy leads to high peaks in the characteristic curves of its kinematic and dynamic performance. For a multiclearance joints mechanism, the maximum impact force at its joints takes its highest value at the nearest joint to the input link. This study also shows that, when the mechanism works in horizontal plane, the rate of impacts at each clearance-joint increases and consequently the clearance-joints and actuators will deteriorate faster.

Analysis of the Dynamic Behavioral Performance of Mechanical Systems With Multi–Clearance Joints

In practice, clearances in the joints are inevitable due to tolerances, and defects arising from design and manufacturing. It is noteworthy that in the presence of clearance at a joint, a mechanism gains some additional, uncontrollable degrees of freedom which are the source of error. Moreover, joints undergo wear and backlashes and so cannot be used in precision mechanisms. In this paper, an optimization method is proposed to alleviate the undesirable effects of joint clearances. The main consideration here is to optimize the mass distribution of links of a mechanism to reduce or eliminate the impact forces in the clearance joints. An algorithm based on PSO solves this highly nonlinear optimization problem for a slider–crank mechanism with revolute clearance joints. Finally, an example is included to demonstrate the efficiency of the algorithm. The results clearly reveal that the linear and angular accelerations of the links and the contact forces in the optimal design are very smooth and bounded.

Dynamic synthesis of a planar slider–crank mechanism with clearances

Synthesis of indexing mechanisms with non-circular gears

Generation of Noncircular Bevel Gears With Free-Form Tooth Profile and Curvilinear Tooth Lengthwise

This study describes rack cutters with circular-arc profile teeth to generate elliptical gears which rotate about one of their foci. A mathematical model for elliptical gears with circular-arc teeth is developed according to gear theory. The influence of the design parameters, such as the number of teeth, gear module, pressure angle at the pitch point and the major-axis, are investigated. The effects of the circular-arc radius of the rack cutter on both the undercutting of teeth and on pointed teeth of the generated circular-arc elliptical gear are also studied. Three numerical examples are presented to elucidate the generation of gear tooth profiles using the proposed mathematical model, and to investigate the phenomena of tooth undercutting and pointed teeth.

Computerized Tooth Profile Generation and Analysis of Characteristics of Elliptical Gears with Circular-Arc Teeth

Linkage model and manufacturing process of shaping non-circular gears

Computerized design and simulation of meshing of modified double circular-arc helical gears by tooth end relief with helix

The mathematical model and mechanical properties of variable center distance gears based on screw theory

The invention discloses a design method for a shrinkage tooth curved-tooth noncircular bevel gear. A knife disk of a standard spiral bevel gear is used as a generating gear, a real tooth surface of the curved-tooth noncircular bevel gear is obtained according to the meshing principle and spatial coordinate transformation, and the generating principle of the curved-tooth noncircular bevel gear is similar to that of a shrinkage tooth spiral bevel gear. The shrinkage tooth curved-tooth noncircular bevel gear designed by the method has a series of advantages that bearing capacity is high, contact ratio is high, and the tooth surface contact area can be regulated; meanwhile, gear ratio transmission of intersecting shafts is achieved, and what is more important is that the shrinkage tooth curved-tooth noncircular bevel gear can be efficiently generated and processed on a five-axis curved-tooth bevel gear milling machine.

Han Xinghui

Papers

Linkage model and manufacturing process of shaping non-circular gears

Synthesis of indexing mechanisms with non-circular gears

Computerized design and simulation of meshing of modified double circular-arc helical gears by tooth end relief with helix

The mathematical model and mechanical properties of variable center distance gears based on screw theory

Design method for shrinkage tooth curved-tooth noncircular bevel gear