Abstract
A design method for the geometric shape and modification of asymmetric spur gear was proposed, in which the geometric shape and modification of the gear can be obtained directly according to the rack-cutter profile. In the geometric design process of the gear, a rack-cutter with different pressure angles and fillet radius in the driving side and coast side was selected, and the generated asymmetric spur gear profiles also had different pressure angles and fillets accordingly. In the modification design of the gear, the pressure angle modification of rack-cutter was conducted firstly and then the corresponding modified involute gear profile was obtained. The geometric model of spur gears was developed using computer-aided design, and the meshing process was analyzed using finite element simulation method. Furthermore, the transmission error and load sharing ratio of unmodified and modified asymmetric spur gears were investigated. Research results showed that the proposed gear design method was feasible and desired spur gear can be obtained through one time rapid machining by the method. Asymmetric spur gear with better transmission characteristic can be obtained via involute modification.
Highlights
Gear drives are one of the most widely used modes in power transmission system with the advantages of large power, high efficiency, and long service life
2ha∗1m, cos α2 where point Q2 is an arbitrary point on line BC, l2 is the variable parameter about the length of straight line BQ2, α2 is the pressure angle representing the slope of line BC, and ρ2 is the radius of fillet curve AB
The theoretic angle at the start of active profile (SAP) is 14.65∘, and theoretic angle at the end of active profile (EAP) is −14.65∘ according to the formula [26]
Summary
Gear drives are one of the most widely used modes in power transmission system with the advantages of large power, high efficiency, and long service life. Litvin et al [3] proposed the modified geometric model of an asymmetric spur gear drive which integrated an involute gear and a double crowned pinion and simulated the meshing and contact process of the spur gears with proposed geometric parameters using computer-aided design method. Alipiev [24] proposed a new geometric design method for the symmetric and asymmetric involute meshing in which the gear load sharing ratio is equal to its expected value. The equations of gear tooth profile were deduced based on a given rack-cutter, and the accurate geometric model was established in the design process. Based on the proposed gear design and modification method, a FEM of asymmetric involute gear was established where computer-aided designs were adopted to establish the geometry model of the spur gears; the meshing process was simulated. The transmission principles of asymmetric spur gear were discussed (Section 4)
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