| The small modulus plastic gear was mainly shaped by injection molding machine. The plastic gear would occur nonlinear shrinkage, In the process of injection molding, due to temperature, pouring environment, the complicated shape of injection molded and many other reasons.This reasons made the tooth profile of the plastic gears and even the gear parameters were different from the original design, and these plastic gears would produce many engineering problems when it is used.I would take the small modulus plastic gear from a toy products made in Vtech Electron Ltd as an example in this paper. I introduced the manufacturing process of small modulus plastic gears, and put forward the shortcomings of molded plastic gears which were made by traditional injection method. I also studied the reansons for quick abrasion on gear addendum and fracture in gear root, after analysed the meshing characteristics of the plactis gears. The result of which was been found is that tooth root modification affect the strength of the tooth root a lot and the tooth root modification affect the fatigue life of gear addendum.From that, I got the best modification ways to improve the property of the gear addendum and root, based on the theory and method of tooth profile modification combing DOE.And I analysed the root strength and addendum abrasion resistance of the modified and non-modified plactis gear, through the software ANSYS Workbench. An engineering physical test has been done to verify the strength and abrasion resistance of the plactis gears, in order to verify the accuracy of software simulation and the rationality of DOE. Eventually, I attained the goal to improve many mechanical properties of plastic gears such as, strength and abrasion resistance, both solved the engineering problems in project, and improved the quality of products and economic benefit of company, what is more, it provided a certain reference for the design of small modulus plastic gear in future. |
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