Numerical Simulation Of Straight Bevel Gear Rolling Process

Gear is an important kind of rotary transmission parts, used for power transmission between two closer axis, which have many advantages, like compact structure, safe and reliable power delivery, long service life, high transmission efficiency, lower noise, accurate and large transmission ratio. They have been widely applied to the field of mechanical transmission. The machinery industry has been developing continuously, and the requirement of the gear’s quality keeps increasing. It is one development direction of the gear plastic forming to eliminate gear defects and improve the quality of gear.Bevel gear rolling process can generate a defect of lug, which will develop into a fold defect in the top of the tooth. It is necessary to find out the reason of the lug generation and design a process to eliminate them. At present, few of studies about how to eliminate the lug defects during the rolling process of the bevel gear were reported. In order to eliminate the lug defects and obtain the perfect bevel gear tooth, this paper focuses on a study for the straight bevel gear rolling process. The models of gears were made by UG and the rolling processes of bevel gear were simulated by DEFORM. On the base of analyzing the forming procedure of the lug defects during the bevel gear rolling process, the mechanism of the lug defect’s generation was recommended. The effect of parameters on forming was also studied,including shear friction factor, the rolling wheel feeding speed, the rolling wheel rotary speed and the fillet radius of the rolling wheel. On the basis, a multi-pass process to eliminate the lug defects in the rolling process of the bevel gear was designed. Main conclusions of this paper are as follows:During the bevel gear rolling process, the contact region between the body and the rolling wheel keeps changing, the right side of the tooth got the force from the bottom to top,and the left side of tooth got the force from the top to bottom. During the deformation process,the surface metal flows faster than the inner. It is the reason for the generation of the lug defect. Further more, the flowing layer of the right side of the tooth is thicker than that of the left side, which makes the right side lug defect higher than the left side.The shear friction factor’s increase makes the right side lug higher, and the maximumdifference is 0.51mm; the height of left side of lug changes little. Rolling wheel feed speed’s increasing makes the right side of lug higher than the left side lug, the maximum height variation of lugs was 0.48 mm and 0.25mm’s respectively. Rolling wheel rotary speed’s increasing makes the right side of the lug lower than the right side lug, the maximum height variation of lugs was 0.48 mm and 0.26mm’s respectively. The change of the radius of the roller tooth has little influence on both sides of the lug defects.Based on the mechanism of the lug formation, a bevel gear multi-pass rolling process was put forward, and the feed account of each rolling pass, which are 2.1mm, 3.6mm, 5.2mm and 6.9mm from first to last rolling, was figured out by the curve calibration method. When forming with the multi-pass process, the rolling wheel’s tooth root can suppresses the inhomogeneous deformation of the metal, limit the formation of the lugs. When the account of the feed is undersize, the lug defects still exist, and when the account of the feed is oversize, the metal will be excessive and then form into the fold defect in the tooth root.