Study On Forming Methods Of Central Boss Of Cylindraceous Gears

Gears are applied wildly in the automobile, aviation, navigation, wind power and other engineering machinery field, which plays a part of driving power and moving. Recently, under the intense competition of automobile industry, producers hope to improve self competition through decreasing production cost of parts, and raise a claim of lightweight and miniaturization of parts, and then the cylindrical gears emerges. External physical characteristic of cylindrical gears are that boss in the center, and the outer is cylinder shape with tooth profile. At present, large quantities of scholars from home and abroad have already made a lot of researches on forming methods of cylindrical gears and made a great achievements, but made a little of researches on plastic processing technology of cylindraceous gears.The questions of traditional burring process for central boss is that the height and quantity is not good enough, so two kinds of process of burring are proposed in this paper, that is upsetting-burring and extruding-burring process, and hope it can improve height and limiting performance.Upsetting-burring process is that through upsetting process to force the thinning metal flowing forward the hole edge, and then using the burring punch to forming the boss. Through the numerical simulation of upsetting-burring process, not only the effects of upsetting stroke, the size of upsetting punch and the taper of lower support, but also the variation regulation of tangential strain and height of central boss with upsetting stroke was analyzed. Finally, all of them were confirmed. Through the contrast with traditional burring process proved that upsetting-burring process can improve the limiting performance of burring process, that is the height and quality of central boss formed by upsetting-burring process is better than traditional burring process.Extruding-burring process is a process like that: firstly, the extruding punch was used to force the head face of cylinder wall of cylindraceous blank, to make the metal in the cylinder wall flowing to center, and then using the burring punch to form the central boss. Through the numerical simulation of extruding-burring process, factors such as the variation regulation of tangential strain and height of central boss with extruding stroke were analyzed. Finally, a part with a central boss of 35mm height was made by physics experiment. Based on the summary on forming methods of central boss, set a cylindraceous gear as target part, assessing both of the structural features and feasibility of forming process, applying the principle of plastic molding, propose a process of plastic forming for cylindraceous gear blank, this process including upsetting, drawing, burring, shaping. Firstly, feasibility of the scheme was proved by empirical formula. In the second place, the forming process was simulated by DEFORM-3D. Lastly, rationality of the process schemes and accuracy of simulation were proved by physical experiments.